diff --git a/Dat/Loaders/SoundObjectLoader.cs b/Dat/Loaders/SoundObjectLoader.cs
index 9e2f7d37..d4eee145 100644
--- a/Dat/Loaders/SoundObjectLoader.cs
+++ b/Dat/Loaders/SoundObjectLoader.cs
@@ -60,7 +60,7 @@ public static LocoObject Load(Stream stream)
 	private static void LoadVariable(LocoBinaryReader br, SoundObject model)
 	{
 		model.NumUnkStructs = br.ReadUInt32();
-		var pcmDataLength = br.ReadUInt32(); // unused
+		_ = br.ReadUInt32(); // unused
 		model.UnkData = br.ReadBytes((int)model.NumUnkStructs * Constants.NumUnkStructs);
 		model.SoundObjectData = new SoundObjectData
 		{
diff --git a/Definitions/Economy.cs b/Definitions/Economy.cs
new file mode 100644
index 00000000..96f28466
--- /dev/null
+++ b/Definitions/Economy.cs
@@ -0,0 +1,76 @@
+namespace Definitions;
+
+/// <summary>
+/// Provides economy-related calculations for Locomotion, including inflation and cost calculations.
+/// Based on OpenLoco's Economy.cpp: https://github.com/OpenLoco/OpenLoco/blob/master/src/OpenLoco/src/Economy/Economy.cpp
+/// </summary>
+public static class Economy
+{
+	// Inflation factors from OpenLoco (kInflationFactors)
+	private static readonly uint[] InflationFactors =
+	[
+		20, 20, 20, 20, 23, 20, 23, 23,
+		20, 17, 17, 20, 20, 20, 20, 20,
+		20, 20, 20, 20, 20, 20, 20, 20,
+		20, 20, 20, 20, 20, 20, 20, 20
+	];
+
+	/// <summary>
+	/// Calculates the currency multiplication factors for all 32 cost indices for a given year.
+	/// </summary>
+	/// <param name="year">The year to calculate inflation for (clamped to 1900-2030 range)</param>
+	/// <returns>An array of 32 currency multiplication factors</returns>
+	public static uint[] CalculateCurrencyMultiplicationFactors(int year)
+	{
+		var factors = new uint[32];
+
+		// Initialize all factors to 1024 (base value)
+		for (var i = 0; i < 32; i++)
+		{
+			factors[i] = 1024;
+		}
+
+		// OpenLoco allows 1800 as the minimum year, whereas Locomotion uses 1900.
+		// Treat years before 1900 as though they were 1900 to not change vanilla scenarios.
+		var baseYear = Math.Clamp(year, 1900, 2030) - 1900;
+		var monthCount = baseYear * 12;
+
+		// Apply inflation for each month
+		for (var month = 0; month < monthCount; month++)
+		{
+			for (var i = 0; i < 32; i++)
+			{
+				factors[i] += (uint)((ulong)InflationFactors[i] * factors[i] >> 12);
+			}
+		}
+
+		return factors;
+	}
+
+	/// <summary>
+	/// Calculates the inflation-adjusted cost for a given cost factor and cost index.
+	/// </summary>
+	/// <param name="costFactor">The base cost factor from the object</param>
+	/// <param name="costIndex">The cost index (0-31)</param>
+	/// <param name="year">The year to calculate the cost for</param>
+	/// <param name="divisor">The divisor to apply (default is 10, which is common for most objects)</param>
+	/// <returns>The inflation-adjusted cost</returns>
+	public static int GetInflationAdjustedCost(short costFactor, byte costIndex, int year, byte divisor = 10)
+	{
+		if (costIndex >= 32)
+		{
+			throw new ArgumentOutOfRangeException(nameof(costIndex), "Cost index must be between 0 and 31");
+		}
+
+		if (divisor >= 63)
+		{
+			throw new ArgumentOutOfRangeException(nameof(divisor), "Divisor must be less than 63");
+		}
+
+		var factors = CalculateCurrencyMultiplicationFactors(year);
+		var val = costFactor * (long)factors[costIndex];
+		var result = val / (1L << divisor);
+
+		return (int)result;
+	}
+}
diff --git a/Definitions/ObjectModels/Graphics/ImageTableGrouper.cs b/Definitions/ObjectModels/Graphics/ImageTableGrouper.cs
index 2ca41267..7def16b0 100644
--- a/Definitions/ObjectModels/Graphics/ImageTableGrouper.cs
+++ b/Definitions/ObjectModels/Graphics/ImageTableGrouper.cs
@@ -13,12 +13,11 @@ public static ImageTable CreateImageTable(ILocoStruct obj, ObjectType objectType
 		ImageTableNamer.NameImages(obj, objectType, imageList);
 
 		var imageTable = new ImageTable();
-
 		try
 		{
 			imageTable.Groups = [.. CreateGroups(obj, objectType, imageList)];
 		}
-		catch (Exception ex)
+		catch (Exception)
 		{
 			imageTable.Groups = [new("<parsing-error>", [.. imageList])];
 		}
diff --git a/Gui/App.axaml b/Gui/App.axaml
index c80484d2..f686c07f 100644
--- a/Gui/App.axaml
+++ b/Gui/App.axaml
@@ -22,6 +22,7 @@
 		<StyleInclude Source="avares://Avalonia.Controls.ColorPicker/Themes/Fluent/Fluent.xaml" />
 		<StyleInclude Source="avares://Avalonia.Controls.TreeDataGrid/Themes/Fluent.axaml" />
 		<StyleInclude Source="/Views/Pos3View.axaml"></StyleInclude>
+		<StyleInclude Source="/Views/InflatableCurrencyView.axaml"></StyleInclude>
 
 		<Style Selector="TabItem">
 			<Setter Property="FontSize" Value="16" />
diff --git a/Gui/Attributes/InflatableCurrencyAttribute.cs b/Gui/Attributes/InflatableCurrencyAttribute.cs
new file mode 100644
index 00000000..7cacf095
--- /dev/null
+++ b/Gui/Attributes/InflatableCurrencyAttribute.cs
@@ -0,0 +1,23 @@
+using System;
+
+namespace Gui.Attributes;
+
+/// <summary>
+/// Marks a property as a currency value that should display with inflation adjustment.
+/// The property must be of type int16_t and have a corresponding CostIndex property.
+/// </summary>
+[AttributeUsage(AttributeTargets.Property)]
+public class InflatableCurrencyAttribute(string CostIndexPropertyName, string? DesignedYearPropertyName = null) : Attribute
+{
+	/// <summary>
+	/// The name of the property that contains the CostIndex for this currency value.
+	/// </summary>
+	public string CostIndexPropertyName { get; } = CostIndexPropertyName;
+
+	/// <summary>
+	/// The name of the property that contains the designed year associated with this currency value.
+	/// This is used as the default year value if it exists.
+	/// Defaults to <see langword="null"/>, meaning no designed year is used.
+	/// </summary>
+	public string DesignedYearPropertyName { get; } = DesignedYearPropertyName;
+}
diff --git a/Gui/Gui.csproj b/Gui/Gui.csproj
index ebb75229..d560051f 100644
--- a/Gui/Gui.csproj
+++ b/Gui/Gui.csproj
@@ -85,6 +85,10 @@
       <DependentUpon>Pos3View.axaml</DependentUpon>
       <SubType>Code</SubType>
     </Compile>
+    <Compile Update="Views\InflatableCurrencyView.axaml.cs">
+      <DependentUpon>InflatableCurrencyView.axaml</DependentUpon>
+      <SubType>Code</SubType>
+    </Compile>
   </ItemGroup>
 
 </Project>
diff --git a/Gui/Models/ObjectEditorModel.cs b/Gui/Models/ObjectEditorModel.cs
index 34890c03..c4bd037e 100644
--- a/Gui/Models/ObjectEditorModel.cs
+++ b/Gui/Models/ObjectEditorModel.cs
@@ -533,7 +533,7 @@ public async Task UploadDatToServer(ObjectIndexEntry dat)
 		}
 
 		// todo: do something with createdObject
-		var createdObject = await ObjectServiceClient.UploadDatFileAsync(dat.FileName, await File.ReadAllBytesAsync(filename), creationDate, modifiedDate);
+		_ = await ObjectServiceClient.UploadDatFileAsync(dat.FileName, await File.ReadAllBytesAsync(filename), creationDate, modifiedDate);
 
 		await Task.Delay(100); // wait 100ms, ie don't DoS the server
 	}
diff --git a/Gui/ViewModels/InflatableCurrencyViewModel.cs b/Gui/ViewModels/InflatableCurrencyViewModel.cs
new file mode 100644
index 00000000..5e3d3649
--- /dev/null
+++ b/Gui/ViewModels/InflatableCurrencyViewModel.cs
@@ -0,0 +1,44 @@
+using Definitions;
+using ReactiveUI;
+
+namespace Gui.ViewModels;
+
+public class InflatableCurrencyViewModel : ReactiveObject
+{
+	public const int DefaultYear = 1950;
+
+	public short CostFactor
+	{
+		get;
+		set
+		{
+			_ = this.RaiseAndSetIfChanged(ref field, value);
+			this.RaisePropertyChanged(nameof(InflationAdjustedCost));
+		}
+	}
+
+	public byte CostIndex
+	{
+		get;
+		set
+		{
+			_ = this.RaiseAndSetIfChanged(ref field, value);
+			this.RaisePropertyChanged(nameof(InflationAdjustedCost));
+		}
+	}
+
+	public int Year
+	{
+		get;
+		set
+		{
+			_ = this.RaiseAndSetIfChanged(ref field, value);
+			this.RaisePropertyChanged(nameof(InflationAdjustedCost));
+		}
+	} = DefaultYear;
+
+	public int InflationAdjustedCost
+		=> CostIndex >= 32
+			? 0
+			: Economy.GetInflationAdjustedCost(CostFactor, CostIndex, Year);
+}
diff --git a/Gui/ViewModels/LocoTypes/ObjectEditorViewModel.cs b/Gui/ViewModels/LocoTypes/ObjectEditorViewModel.cs
index 4966b28d..d71a5026 100644
--- a/Gui/ViewModels/LocoTypes/ObjectEditorViewModel.cs
+++ b/Gui/ViewModels/LocoTypes/ObjectEditorViewModel.cs
@@ -125,7 +125,7 @@ void ValidateForOG()
 		}
 
 		// split the CurrentFile path on "opengraphics" folder
-		var dir = Path.GetRelativePath(Model.Settings.ObjDataDirectory, CurrentFile.FileName);
+		_ = Path.GetRelativePath(Model.Settings.ObjDataDirectory, CurrentFile.FileName);
 		var parentDirName = Path.GetFileName(Path.GetDirectoryName(CurrentFile.FileName));
 
 		if (OriginalObjectFiles.Names.TryGetValue(parentDirName, out var fileInfo))
@@ -398,7 +398,7 @@ void SaveCore(string filename, SaveParameters saveParameters)
 		CurrentObjectViewModel.CopyBackToModel();
 
 		// this is hacky but it should work
-		if (ExtraContentViewModel is AudioViewModel avm && CurrentObject.LocoObject.Object is SoundObject so)
+		if (ExtraContentViewModel is AudioViewModel avm && CurrentObject.LocoObject.Object is SoundObject)
 		{
 			var datWav = avm.GetAsDatWav(LocoAudioType.SoundEffect);
 			if (datWav == null)
diff --git a/Gui/ViewModels/LocoTypes/Objects/AirportViewModel.cs b/Gui/ViewModels/LocoTypes/Objects/AirportViewModel.cs
index b8672ce6..04cb8b2a 100644
--- a/Gui/ViewModels/LocoTypes/Objects/AirportViewModel.cs
+++ b/Gui/ViewModels/LocoTypes/Objects/AirportViewModel.cs
@@ -1,8 +1,10 @@
 using Dat.Loaders;
 using Definitions.ObjectModels.Objects.Airport;
 using Definitions.ObjectModels.Objects.Common;
+using Gui.Attributes;
 using PropertyModels.ComponentModel.DataAnnotations;
 using PropertyModels.Extensions;
+using ReactiveUI;
 using System.ComponentModel;
 using System.ComponentModel.DataAnnotations;
 using System.Linq;
@@ -65,17 +67,22 @@ public uint32_t LargeTiles
 	public uint8_t CostIndex
 	{
 		get => Model.CostIndex;
-		set => Model.CostIndex = value;
+		set
+		{
+			Model.CostIndex = value;
+			this.RaisePropertyChanged(nameof(BuildCostFactor));
+			this.RaisePropertyChanged(nameof(SellCostFactor));
+		}
 	}
 
-	[Category("Cost")]
+	[Category("Cost"), InflatableCurrency(nameof(CostIndex), nameof(DesignedYear))]
 	public int16_t BuildCostFactor
 	{
 		get => Model.BuildCostFactor;
 		set => Model.BuildCostFactor = value;
 	}
 
-	[Category("Cost")]
+	[Category("Cost"), InflatableCurrency(nameof(CostIndex), nameof(DesignedYear))]
 	public int16_t SellCostFactor
 	{
 		get => Model.SellCostFactor;
diff --git a/Gui/ViewModels/LocoTypes/Objects/BridgeViewModel.cs b/Gui/ViewModels/LocoTypes/Objects/BridgeViewModel.cs
index 5a860eab..c3af1251 100644
--- a/Gui/ViewModels/LocoTypes/Objects/BridgeViewModel.cs
+++ b/Gui/ViewModels/LocoTypes/Objects/BridgeViewModel.cs
@@ -1,6 +1,8 @@
 using Definitions.ObjectModels.Objects.Bridge;
 using Definitions.ObjectModels.Types;
+using Gui.Attributes;
 using PropertyModels.ComponentModel.DataAnnotations;
+using ReactiveUI;
 using System.ComponentModel;
 
 namespace Gui.ViewModels;
@@ -68,24 +70,30 @@ public uint16_t DesignedYear
 	public uint8_t CostIndex
 	{
 		get => Model.CostIndex;
-		set => Model.CostIndex = value;
+		set
+		{
+			Model.CostIndex = value;
+			this.RaisePropertyChanged(nameof(BaseCostFactor));
+			this.RaisePropertyChanged(nameof(HeightCostFactor));
+			this.RaisePropertyChanged(nameof(SellCostFactor));
+		}
 	}
 
-	[Category("Cost")]
+	[Category("Cost"), InflatableCurrency(nameof(CostIndex), nameof(DesignedYear))]
 	public int16_t BaseCostFactor
 	{
 		get => Model.BaseCostFactor;
 		set => Model.BaseCostFactor = value;
 	}
 
-	[Category("Cost")]
+	[Category("Cost"), InflatableCurrency(nameof(CostIndex), nameof(DesignedYear))]
 	public int16_t HeightCostFactor
 	{
 		get => Model.HeightCostFactor;
 		set => Model.HeightCostFactor = value;
 	}
 
-	[Category("Cost")]
+	[Category("Cost"), InflatableCurrency(nameof(CostIndex), nameof(DesignedYear))]
 	public int16_t SellCostFactor
 	{
 		get => Model.SellCostFactor;
diff --git a/Gui/ViewModels/LocoTypes/Objects/DockViewModel.cs b/Gui/ViewModels/LocoTypes/Objects/DockViewModel.cs
index 9671277a..267b4c35 100644
--- a/Gui/ViewModels/LocoTypes/Objects/DockViewModel.cs
+++ b/Gui/ViewModels/LocoTypes/Objects/DockViewModel.cs
@@ -2,8 +2,10 @@
 using Definitions.ObjectModels.Objects.Common;
 using Definitions.ObjectModels.Objects.Dock;
 using Definitions.ObjectModels.Types;
+using Gui.Attributes;
 using PropertyModels.ComponentModel.DataAnnotations;
 using PropertyModels.Extensions;
+using ReactiveUI;
 using System.ComponentModel;
 using System.ComponentModel.DataAnnotations;
 using System.Linq;
@@ -42,17 +44,22 @@ public Pos2 BoatPosition
 	public uint8_t CostIndex
 	{
 		get => Model.CostIndex;
-		set => Model.CostIndex = value;
+		set
+		{
+			Model.CostIndex = value;
+			this.RaisePropertyChanged(nameof(BuildCostFactor));
+			this.RaisePropertyChanged(nameof(SellCostFactor));
+		}
 	}
 
-	[Category("Cost")]
+	[Category("Cost"), InflatableCurrency(nameof(CostIndex), nameof(DesignedYear))]
 	public int16_t BuildCostFactor
 	{
 		get => Model.BuildCostFactor;
 		set => Model.BuildCostFactor = value;
 	}
 
-	[Category("Cost")]
+	[Category("Cost"), InflatableCurrency(nameof(CostIndex), nameof(DesignedYear))]
 	public int16_t SellCostFactor
 	{
 		get => Model.SellCostFactor;
diff --git a/Gui/ViewModels/LocoTypes/Objects/IndustryViewModel.cs b/Gui/ViewModels/LocoTypes/Objects/IndustryViewModel.cs
index fe3e2bf2..66a1b53b 100644
--- a/Gui/ViewModels/LocoTypes/Objects/IndustryViewModel.cs
+++ b/Gui/ViewModels/LocoTypes/Objects/IndustryViewModel.cs
@@ -3,8 +3,10 @@
 using Definitions.ObjectModels.Objects.Common;
 using Definitions.ObjectModels.Objects.Industry;
 using Definitions.ObjectModels.Types;
+using Gui.Attributes;
 using PropertyModels.ComponentModel.DataAnnotations;
 using PropertyModels.Extensions;
+using ReactiveUI;
 using System.ComponentModel;
 using System.ComponentModel.DataAnnotations;
 using System.Linq;
@@ -76,17 +78,22 @@ public uint8_t MonthlyClosureChance
 	public uint8_t CostIndex
 	{
 		get => Model.CostIndex;
-		set => Model.CostIndex = value;
+		set
+		{
+			Model.CostIndex = value;
+			this.RaisePropertyChanged(nameof(BuildCostFactor));
+			this.RaisePropertyChanged(nameof(SellCostFactor));
+		}
 	}
 
-	[Category("Cost")]
+	[Category("Cost"), InflatableCurrency(nameof(CostIndex), nameof(DesignedYear))]
 	public int16_t BuildCostFactor
 	{
 		get => Model.BuildCostFactor;
 		set => Model.BuildCostFactor = value;
 	}
 
-	[Category("Cost")]
+	[Category("Cost"), InflatableCurrency(nameof(CostIndex), nameof(DesignedYear))]
 	public int16_t SellCostFactor
 	{
 		get => Model.SellCostFactor;
diff --git a/Gui/ViewModels/LocoTypes/Objects/RoadExtraViewModel.cs b/Gui/ViewModels/LocoTypes/Objects/RoadExtraViewModel.cs
index ec90d80c..3db81970 100644
--- a/Gui/ViewModels/LocoTypes/Objects/RoadExtraViewModel.cs
+++ b/Gui/ViewModels/LocoTypes/Objects/RoadExtraViewModel.cs
@@ -1,6 +1,9 @@
 using Definitions.ObjectModels.Objects.Road;
 using Definitions.ObjectModels.Objects.RoadExtra;
+using Gui.Attributes;
 using PropertyModels.ComponentModel.DataAnnotations;
+using ReactiveUI;
+using System.ComponentModel;
 
 namespace Gui.ViewModels;
 
@@ -20,18 +23,26 @@ public uint8_t PaintStyle
 		set => Model.PaintStyle = value;
 	}
 
+	[Category("Cost")]
 	public uint8_t CostIndex
 	{
 		get => Model.CostIndex;
-		set => Model.CostIndex = value;
+		set
+		{
+			Model.CostIndex = value;
+			this.RaisePropertyChanged(nameof(BuildCostFactor));
+			this.RaisePropertyChanged(nameof(SellCostFactor));
+		}
 	}
 
+	[Category("Cost"), InflatableCurrency(nameof(CostIndex))]
 	public int16_t BuildCostFactor
 	{
 		get => Model.BuildCostFactor;
 		set => Model.BuildCostFactor = value;
 	}
 
+	[Category("Cost"), InflatableCurrency(nameof(CostIndex))]
 	public int16_t SellCostFactor
 	{
 		get => Model.SellCostFactor;
diff --git a/Gui/ViewModels/LocoTypes/Objects/RoadStationViewModel.cs b/Gui/ViewModels/LocoTypes/Objects/RoadStationViewModel.cs
index b1d62cb7..0e368ed5 100644
--- a/Gui/ViewModels/LocoTypes/Objects/RoadStationViewModel.cs
+++ b/Gui/ViewModels/LocoTypes/Objects/RoadStationViewModel.cs
@@ -2,7 +2,9 @@
 using Definitions.ObjectModels.Objects.RoadStation;
 using Definitions.ObjectModels.Objects.Shared;
 using Definitions.ObjectModels.Types;
+using Gui.Attributes;
 using PropertyModels.ComponentModel.DataAnnotations;
+using ReactiveUI;
 using System.ComponentModel;
 
 namespace Gui.ViewModels;
@@ -50,26 +52,31 @@ public RoadStationObjectFlags Flags
 	}
 
 	[Category("Cost")]
+	public uint8_t CostIndex
+	{
+		get => Model.CostIndex;
+		set
+		{
+			Model.CostIndex = value;
+			this.RaisePropertyChanged(nameof(BuildCostFactor));
+			this.RaisePropertyChanged(nameof(SellCostFactor));
+		}
+	}
+
+	[Category("Cost"), InflatableCurrency(nameof(CostIndex), nameof(DesignedYear))]
 	public int16_t BuildCostFactor
 	{
 		get => Model.BuildCostFactor;
 		set => Model.BuildCostFactor = value;
 	}
 
-	[Category("Cost")]
+	[Category("Cost"), InflatableCurrency(nameof(CostIndex), nameof(DesignedYear))]
 	public int16_t SellCostFactor
 	{
 		get => Model.SellCostFactor;
 		set => Model.SellCostFactor = value;
 	}
 
-	[Category("Cost")]
-	public uint8_t CostIndex
-	{
-		get => Model.CostIndex;
-		set => Model.CostIndex = value;
-	}
-
 	[Category("Cargo")]
 	public ObjectModelHeader? CargoType
 	{
diff --git a/Gui/ViewModels/LocoTypes/Objects/RoadViewModel.cs b/Gui/ViewModels/LocoTypes/Objects/RoadViewModel.cs
index 2cdf9604..47034ec2 100644
--- a/Gui/ViewModels/LocoTypes/Objects/RoadViewModel.cs
+++ b/Gui/ViewModels/LocoTypes/Objects/RoadViewModel.cs
@@ -1,6 +1,8 @@
 using Definitions.ObjectModels.Objects.Road;
 using Definitions.ObjectModels.Types;
+using Gui.Attributes;
 using PropertyModels.ComponentModel.DataAnnotations;
+using ReactiveUI;
 using System.ComponentModel;
 
 namespace Gui.ViewModels;
@@ -48,33 +50,39 @@ public TownSize TargetTownSize
 	}
 
 	[Category("Cost")]
+	public uint8_t CostIndex
+	{
+		get => Model.CostIndex;
+		set
+		{
+			Model.CostIndex = value;
+			this.RaisePropertyChanged(nameof(BuildCostFactor));
+			this.RaisePropertyChanged(nameof(SellCostFactor));
+			this.RaisePropertyChanged(nameof(TunnelCostFactor));
+		}
+	}
+
+	[Category("Cost"), InflatableCurrency(nameof(CostIndex))]
 	public int16_t BuildCostFactor
 	{
 		get => Model.BuildCostFactor;
 		set => Model.BuildCostFactor = value;
 	}
 
-	[Category("Cost")]
+	[Category("Cost"), InflatableCurrency(nameof(CostIndex))]
 	public int16_t SellCostFactor
 	{
 		get => Model.SellCostFactor;
 		set => Model.SellCostFactor = value;
 	}
 
-	[Category("Cost")]
+	[Category("Cost"), InflatableCurrency(nameof(CostIndex))]
 	public int16_t TunnelCostFactor
 	{
 		get => Model.TunnelCostFactor;
 		set => Model.TunnelCostFactor = value;
 	}
 
-	[Category("Cost")]
-	public uint8_t CostIndex
-	{
-		get => Model.CostIndex;
-		set => Model.CostIndex = value;
-	}
-
 	[Category("Compatible Objects")]
 	public ObjectModelHeader Tunnel
 	{
diff --git a/Gui/ViewModels/LocoTypes/Objects/TrackExtraViewModel.cs b/Gui/ViewModels/LocoTypes/Objects/TrackExtraViewModel.cs
index fba89e15..25d910f8 100644
--- a/Gui/ViewModels/LocoTypes/Objects/TrackExtraViewModel.cs
+++ b/Gui/ViewModels/LocoTypes/Objects/TrackExtraViewModel.cs
@@ -1,6 +1,9 @@
 using Definitions.ObjectModels.Objects.Track;
 using Definitions.ObjectModels.Objects.TrackExtra;
+using Gui.Attributes;
 using PropertyModels.ComponentModel.DataAnnotations;
+using ReactiveUI;
+using System.ComponentModel;
 
 namespace Gui.ViewModels;
 
@@ -20,18 +23,26 @@ public uint8_t PaintStyle
 		set => Model.PaintStyle = value;
 	}
 
+	[Category("Cost")]
 	public uint8_t CostIndex
 	{
 		get => Model.CostIndex;
-		set => Model.CostIndex = value;
+		set
+		{
+			Model.CostIndex = value;
+			this.RaisePropertyChanged(nameof(BuildCostFactor));
+			this.RaisePropertyChanged(nameof(SellCostFactor));
+		}
 	}
 
+	[Category("Cost"), InflatableCurrency(nameof(CostIndex))]
 	public int16_t BuildCostFactor
 	{
 		get => Model.BuildCostFactor;
 		set => Model.BuildCostFactor = value;
 	}
 
+	[Category("Cost"), InflatableCurrency(nameof(CostIndex))]
 	public int16_t SellCostFactor
 	{
 		get => Model.SellCostFactor;
diff --git a/Gui/ViewModels/LocoTypes/Objects/TrackSignalViewModel.cs b/Gui/ViewModels/LocoTypes/Objects/TrackSignalViewModel.cs
index 2e5d1f50..1e254494 100644
--- a/Gui/ViewModels/LocoTypes/Objects/TrackSignalViewModel.cs
+++ b/Gui/ViewModels/LocoTypes/Objects/TrackSignalViewModel.cs
@@ -1,7 +1,9 @@
 using Dat.Loaders;
 using Definitions.ObjectModels.Objects.TrackSignal;
 using Definitions.ObjectModels.Types;
+using Gui.Attributes;
 using PropertyModels.ComponentModel.DataAnnotations;
+using ReactiveUI;
 using System.ComponentModel;
 using System.ComponentModel.DataAnnotations;
 
@@ -33,17 +35,22 @@ public uint8_t NumFrames
 	public uint8_t CostIndex
 	{
 		get => Model.CostIndex;
-		set => Model.CostIndex = value;
+		set
+		{
+			Model.CostIndex = value;
+			this.RaisePropertyChanged(nameof(BuildCostFactor));
+			this.RaisePropertyChanged(nameof(SellCostFactor));
+		}
 	}
 
-	[Category("Cost")]
+	[Category("Cost"), InflatableCurrency(nameof(CostIndex), nameof(DesignedYear))]
 	public int16_t BuildCostFactor
 	{
 		get => Model.BuildCostFactor;
 		set => Model.BuildCostFactor = value;
 	}
 
-	[Category("Cost")]
+	[Category("Cost"), InflatableCurrency(nameof(CostIndex), nameof(DesignedYear))]
 	public int16_t SellCostFactor
 	{
 		get => Model.SellCostFactor;
diff --git a/Gui/ViewModels/LocoTypes/Objects/TrackStationViewModel.cs b/Gui/ViewModels/LocoTypes/Objects/TrackStationViewModel.cs
index 8e22626c..7db4ea0b 100644
--- a/Gui/ViewModels/LocoTypes/Objects/TrackStationViewModel.cs
+++ b/Gui/ViewModels/LocoTypes/Objects/TrackStationViewModel.cs
@@ -2,7 +2,9 @@
 using Definitions.ObjectModels.Objects.Track;
 using Definitions.ObjectModels.Objects.TrackStation;
 using Definitions.ObjectModels.Types;
+using Gui.Attributes;
 using PropertyModels.ComponentModel.DataAnnotations;
+using ReactiveUI;
 using System.ComponentModel;
 
 namespace Gui.ViewModels;
@@ -49,26 +51,31 @@ public TrackStationObjectFlags Flags
 	}
 
 	[Category("Cost")]
+	public uint8_t CostIndex
+	{
+		get => Model.CostIndex;
+		set
+		{
+			Model.CostIndex = value;
+			this.RaisePropertyChanged(nameof(BuildCostFactor));
+			this.RaisePropertyChanged(nameof(SellCostFactor));
+		}
+	}
+
+	[Category("Cost"), InflatableCurrency(nameof(CostIndex), nameof(DesignedYear))]
 	public int16_t BuildCostFactor
 	{
 		get => Model.BuildCostFactor;
 		set => Model.BuildCostFactor = value;
 	}
 
-	[Category("Cost")]
+	[Category("Cost"), InflatableCurrency(nameof(CostIndex), nameof(DesignedYear))]
 	public int16_t SellCostFactor
 	{
 		get => Model.SellCostFactor;
 		set => Model.SellCostFactor = value;
 	}
 
-	[Category("Cost")]
-	public uint8_t CostIndex
-	{
-		get => Model.CostIndex;
-		set => Model.CostIndex = value;
-	}
-
 	[Category("<unknown>")]
 	public uint8_t var_0B
 	{
diff --git a/Gui/ViewModels/LocoTypes/Objects/TrackViewModel.cs b/Gui/ViewModels/LocoTypes/Objects/TrackViewModel.cs
index caef060f..29e326a0 100644
--- a/Gui/ViewModels/LocoTypes/Objects/TrackViewModel.cs
+++ b/Gui/ViewModels/LocoTypes/Objects/TrackViewModel.cs
@@ -1,6 +1,8 @@
 using Definitions.ObjectModels.Objects.Track;
 using Definitions.ObjectModels.Types;
+using Gui.Attributes;
 using PropertyModels.ComponentModel.DataAnnotations;
+using ReactiveUI;
 using System.ComponentModel;
 using TrackObject = Definitions.ObjectModels.Objects.Track.TrackObject;
 
@@ -44,33 +46,39 @@ public uint8_t VehicleDisplayListVerticalOffset
 	}
 
 	[Category("Cost")]
+	public uint8_t CostIndex
+	{
+		get => Model.CostIndex;
+		set
+		{
+			Model.CostIndex = value;
+			this.RaisePropertyChanged(nameof(BuildCostFactor));
+			this.RaisePropertyChanged(nameof(SellCostFactor));
+			this.RaisePropertyChanged(nameof(TunnelCostFactor));
+		}
+	}
+
+	[Category("Cost"), InflatableCurrency(nameof(CostIndex))]
 	public int16_t BuildCostFactor
 	{
 		get => Model.BuildCostFactor;
 		set => Model.BuildCostFactor = value;
 	}
 
-	[Category("Cost")]
+	[Category("Cost"), InflatableCurrency(nameof(CostIndex))]
 	public int16_t SellCostFactor
 	{
 		get => Model.SellCostFactor;
 		set => Model.SellCostFactor = value;
 	}
 
-	[Category("Cost")]
+	[Category("Cost"), InflatableCurrency(nameof(CostIndex))]
 	public int16_t TunnelCostFactor
 	{
 		get => Model.TunnelCostFactor;
 		set => Model.TunnelCostFactor = value;
 	}
 
-	[Category("Cost")]
-	public uint8_t CostIndex
-	{
-		get => Model.CostIndex;
-		set => Model.CostIndex = value;
-	}
-
 	[Category("<unknown>")]
 	public uint8_t var_06
 	{
diff --git a/Gui/ViewModels/LocoTypes/Objects/TreeViewModel.cs b/Gui/ViewModels/LocoTypes/Objects/TreeViewModel.cs
index a657bdf5..e8af3c4c 100644
--- a/Gui/ViewModels/LocoTypes/Objects/TreeViewModel.cs
+++ b/Gui/ViewModels/LocoTypes/Objects/TreeViewModel.cs
@@ -1,5 +1,7 @@
 using Definitions.ObjectModels.Objects.Tree;
+using Gui.Attributes;
 using PropertyModels.ComponentModel.DataAnnotations;
+using ReactiveUI;
 using System.ComponentModel;
 
 namespace Gui.ViewModels;
@@ -48,17 +50,22 @@ public uint32_t Colours
 	public uint8_t CostIndex
 	{
 		get => Model.CostIndex;
-		set => Model.CostIndex = value;
+		set
+		{
+			Model.CostIndex = value;
+			this.RaisePropertyChanged(nameof(BuildCostFactor));
+			this.RaisePropertyChanged(nameof(ClearCostFactor));
+		}
 	}
 
-	[Category("Cost")]
+	[Category("Cost"), InflatableCurrency(nameof(CostIndex))]
 	public int16_t BuildCostFactor
 	{
 		get => Model.BuildCostFactor;
 		set => Model.BuildCostFactor = value;
 	}
 
-	[Category("Cost")]
+	[Category("Cost"), InflatableCurrency(nameof(CostIndex))]
 	public int16_t ClearCostFactor
 	{
 		get => Model.ClearCostFactor;
diff --git a/Gui/ViewModels/LocoTypes/Objects/VehicleViewModel.cs b/Gui/ViewModels/LocoTypes/Objects/VehicleViewModel.cs
index ac353d5f..ead069f9 100644
--- a/Gui/ViewModels/LocoTypes/Objects/VehicleViewModel.cs
+++ b/Gui/ViewModels/LocoTypes/Objects/VehicleViewModel.cs
@@ -4,6 +4,7 @@
 using Definitions.ObjectModels.Types;
 using DynamicData.Binding;
 using PropertyModels.ComponentModel;
+using Gui.Attributes;
 using PropertyModels.ComponentModel.DataAnnotations;
 using PropertyModels.Extensions;
 using ReactiveUI;
@@ -250,11 +251,15 @@ public uint8_t ShipWakeSpacing
 	public uint8_t CostIndex
 	{
 		get => model.CostIndex;
-		set => model.CostIndex = value;
+		set
+		{
+			Model.CostIndex = value;
+			this.RaisePropertyChanged(nameof(CostFactor));
+		}
 	}
 
 	[Category("Cost")]
-	[Range(1, int16_t.MaxValue)]
+	[Range(1, int16_t.MaxValue), InflatableCurrency(nameof(CostIndex), nameof(DesignedYear))]
 	public int16_t CostFactor
 	{
 		get => model.CostFactor;
@@ -266,11 +271,15 @@ public int16_t CostFactor
 	public uint8_t RunCostIndex
 	{
 		get => model.RunCostIndex;
-		set => model.RunCostIndex = value;
+		set
+		{
+			Model.RunCostIndex = value;
+			this.RaisePropertyChanged(nameof(RunCostFactor));
+		}
 	}
 
 	[Category("Cost")]
-	[Range(0, int16_t.MaxValue)]
+	[Range(0, int16_t.MaxValue), InflatableCurrency(nameof(RunCostIndex), nameof(DesignedYear))]
 	public int16_t RunCostFactor
 	{
 		get => model.RunCostFactor;
diff --git a/Gui/ViewModels/LocoTypes/Objects/WaterViewModel.cs b/Gui/ViewModels/LocoTypes/Objects/WaterViewModel.cs
index 7361dae6..142adfe1 100644
--- a/Gui/ViewModels/LocoTypes/Objects/WaterViewModel.cs
+++ b/Gui/ViewModels/LocoTypes/Objects/WaterViewModel.cs
@@ -1,25 +1,34 @@
 using Definitions.ObjectModels.Objects.Water;
+using Gui.Attributes;
+using ReactiveUI;
+using System.ComponentModel;
 
 namespace Gui.ViewModels;
 
 public class WaterViewModel(WaterObject model)
 	: LocoObjectViewModel<WaterObject>(model)
 {
+	[Category("Cost")]
 	public uint8_t CostIndex
 	{
 		get => Model.CostIndex;
-		set => Model.CostIndex = value;
+		set
+		{
+			Model.CostIndex = value;
+			this.RaisePropertyChanged(nameof(CostFactor));
+		}
 	}
 
+	[Category("Cost"), InflatableCurrency(nameof(CostIndex))]
+	public int16_t CostFactor
+	{
+		get => Model.CostFactor;
+		set => Model.CostFactor = value;
+	}
 	public uint8_t var_03
 	{
 		get => Model.var_03;
 		set => Model.var_03 = value;
 	}
 
-	public int16_t CostFactor
-	{
-		get => Model.CostFactor;
-		set => Model.CostFactor = value;
-	}
 }
diff --git a/Gui/Views/ExtendedPropertyGrid.cs b/Gui/Views/ExtendedPropertyGrid.cs
index 10a12f8f..8b1fae79 100644
--- a/Gui/Views/ExtendedPropertyGrid.cs
+++ b/Gui/Views/ExtendedPropertyGrid.cs
@@ -2,7 +2,10 @@
 using Avalonia.PropertyGrid.Controls;
 using Avalonia.PropertyGrid.Controls.Factories;
 using Definitions.ObjectModels.Types;
+using Gui.Attributes;
 using Gui.ViewModels;
+using System.ComponentModel;
+using System.Linq;
 
 namespace Gui.Views;
 
@@ -11,12 +14,14 @@ public class ExtendedPropertyGrid : PropertyGrid
 	public ExtendedPropertyGrid()
 	{
 		Factories.AddFactory(new Pos3CellEditFactory());
+		Factories.AddFactory(new InflatableCurrencyCellEditFactory());
 	}
 }
 
 internal class Pos3CellEditFactory : AbstractCellEditFactory
 {
-	public override bool Accept(object accessToken) => accessToken is ExtendedPropertyGrid;
+	public override bool Accept(object accessToken)
+		=> accessToken is ExtendedPropertyGrid;
 
 	public override Control? HandleNewProperty(PropertyCellContext context)
 	{
@@ -28,9 +33,7 @@ internal class Pos3CellEditFactory : AbstractCellEditFactory
 			return null;
 		}
 
-		var control = new Pos3View();
-
-		return control;
+		return new Pos3View();
 	}
 
 	public override bool HandlePropertyChanged(PropertyCellContext context)
@@ -46,15 +49,97 @@ public override bool HandlePropertyChanged(PropertyCellContext context)
 
 		ValidateProperty(control, propertyDescriptor, target);
 
-		if (control is Pos3View vv)
+		if (control is Pos3View pv)
 		{
 			var pos = (Pos3)propertyDescriptor.GetValue(target)!;
 
 			var model = new Pos3ViewModel { Pos = pos };
-			vv.DataContext = model;
+			pv.DataContext = model;
 
 			model.PropertyChanged += (s, e) => SetAndRaise(context, control, model.Pos);
+			return true;
+		}
+
+		return false;
+	}
+}
+
+internal class InflatableCurrencyCellEditFactory : AbstractCellEditFactory
+{
+	public override bool Accept(object accessToken)
+		=> accessToken is ExtendedPropertyGrid;
+
+	public override Control? HandleNewProperty(PropertyCellContext context)
+	{
+		var propertyDescriptor = context.Property;
+		_ = context.Target;
+
+		var currencyAttr = propertyDescriptor.Attributes.OfType<InflatableCurrencyAttribute>().FirstOrDefault();
+		if (currencyAttr == null)
+		{
+			return null;
+		}
+
+		if (propertyDescriptor.PropertyType != typeof(short))
+		{
+			return null;
+		}
+
+		return new InflatableCurrencyView();
+	}
+
+	public override bool HandlePropertyChanged(PropertyCellContext context)
+	{
+		var propertyDescriptor = context.Property;
+		var target = context.Target;
+		var control = context.CellEdit!;
+
+		var currencyAttr = propertyDescriptor.Attributes.OfType<InflatableCurrencyAttribute>().FirstOrDefault();
+		if (currencyAttr == null || propertyDescriptor.PropertyType != typeof(short))
+		{
+			return false;
+		}
+
+		ValidateProperty(control, propertyDescriptor, target);
+
+		if (control is InflatableCurrencyView cv)
+		{
+			if (cv is null)
+			{
+				return false;
+			}
+
+			var costFactor = (short)propertyDescriptor.GetValue(target)!;
+
+			// Get CostIndex from the target object
+			var costIndexProperty = TypeDescriptor.GetProperties(target)[currencyAttr.CostIndexPropertyName];
+			var costIndex = costIndexProperty != null
+				? (uint8_t)costIndexProperty.GetValue(target)!
+				: (uint8_t)0;
+
+			var designedYearProperty = TypeDescriptor.GetProperties(target)[currencyAttr.DesignedYearPropertyName];
+			var designedYear = designedYearProperty != null
+				? (uint16_t)designedYearProperty.GetValue(target)!
+				: (uint16_t)1950;
+
+			var currVm = (InflatableCurrencyViewModel?)cv?.DataContext;
+			var year = currVm?.Year ?? designedYear;
+			// objects can actually set any year as designed year, even 0, so lets sanitize it
+			if (year < 1800)
+			{
+				year = InflatableCurrencyViewModel.DefaultYear;
+			}
+
+			var model = new InflatableCurrencyViewModel
+			{
+				CostFactor = costFactor,
+				CostIndex = costIndex,
+				Year = year
+			};
+
+			cv.DataContext = model;
 
+			model.PropertyChanged += (s, e) => SetAndRaise(context, control, model.CostFactor);
 			return true;
 		}
 
diff --git a/Gui/Views/InflatableCurrencyView.axaml b/Gui/Views/InflatableCurrencyView.axaml
new file mode 100644
index 00000000..df60b966
--- /dev/null
+++ b/Gui/Views/InflatableCurrencyView.axaml
@@ -0,0 +1,47 @@
+<Styles
+	xmlns="https://github.com/avaloniaui"
+	xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+	xmlns:vi="using:Gui.Views"
+	xmlns:vm="using:Gui.ViewModels">
+	<Design.PreviewWith>
+		<vi:InflatableCurrencyView />
+	</Design.PreviewWith>
+
+	<Style Selector="vi|InflatableCurrencyView">
+		<Setter Property="Template">
+			<ControlTemplate>
+				<StackPanel x:DataType="vm:InflatableCurrencyViewModel" Orientation="Horizontal" Spacing="4">
+					<!-- Cost Factor Input -->
+					<!--<TextBlock Text="Factor:" VerticalAlignment="Center" />-->
+					<NumericUpDown Value="{Binding CostFactor}" 
+								   ShowButtonSpinner="True"
+								   Minimum="-32768"
+								   Maximum="32767"
+								   Width="128"
+								   FormatString="F0"
+								   ParsingNumberStyle="Integer">
+					</NumericUpDown>
+					
+					<!-- Year Input -->
+					<TextBlock Text="Year:" VerticalAlignment="Center" />
+					<NumericUpDown Value="{Binding Year}" 
+								   ShowButtonSpinner="True"
+								   Minimum="1800"
+								   Maximum="2100"
+								   Width="128"
+								   FormatString="F0"
+								   ParsingNumberStyle="Integer">
+					</NumericUpDown>
+					
+					<!-- Effective Cost Display -->
+					<TextBlock Text="→" VerticalAlignment="Center" />
+					<TextBox Text="{Binding InflationAdjustedCost}"
+							   VerticalAlignment="Center" 
+							   FontWeight="Bold"
+							   Width="64"
+							   IsReadOnly="True"/>
+				</StackPanel>
+			</ControlTemplate>
+		</Setter>
+	</Style>
+</Styles>
diff --git a/Gui/Views/InflatableCurrencyView.cs b/Gui/Views/InflatableCurrencyView.cs
new file mode 100644
index 00000000..498bcd3f
--- /dev/null
+++ b/Gui/Views/InflatableCurrencyView.cs
@@ -0,0 +1,5 @@
+using Avalonia.Controls.Primitives;
+
+namespace Gui.Views;
+
+public class InflatableCurrencyView : TemplatedControl;
diff --git a/Gui/Views/Pos3View.axaml b/Gui/Views/Pos3View.axaml
index f4772b4a..df7d8ddc 100644
--- a/Gui/Views/Pos3View.axaml
+++ b/Gui/Views/Pos3View.axaml
@@ -8,22 +8,21 @@
 	</Design.PreviewWith>
 
 	<Style Selector="vi|Pos3View">
-		<!-- Set Defaults -->
 		<Setter Property="Template">
 			<ControlTemplate>
 				<StackPanel x:DataType="vm:Pos3ViewModel" Orientation="Horizontal">
+					<!-- X -->
 					<TextBlock Text="X" VerticalAlignment="Center" Padding="4"></TextBlock>
-					<!-- ReSharper disable once Xaml.BindingWithoutContextNotResolved -->
 					<NumericUpDown Value="{Binding X}"  ShowButtonSpinner="False">
 						<NumericUpDown.FormatString>{0}</NumericUpDown.FormatString>
 					</NumericUpDown>
+					<!-- Y -->
 					<TextBlock Text="Y" VerticalAlignment="Center" Padding="4"></TextBlock>
-					<!-- ReSharper disable once Xaml.BindingWithoutContextNotResolved -->
 					<NumericUpDown Value="{Binding Y}" ShowButtonSpinner="False">
 						<NumericUpDown.FormatString>{0}</NumericUpDown.FormatString>
 					</NumericUpDown>
+					<!-- Z -->
 					<TextBlock Text="Z" VerticalAlignment="Center" Padding="4"></TextBlock>
-					<!-- ReSharper disable once Xaml.BindingWithoutContextNotResolved -->
 					<NumericUpDown Value="{Binding Z}" ShowButtonSpinner="False">
 						<NumericUpDown.FormatString>{0}</NumericUpDown.FormatString>
 					</NumericUpDown>
diff --git a/ObjectService/ServerFolderManager.cs b/ObjectService/ServerFolderManager.cs
index d8c7e6b0..9c08a10c 100644
--- a/ObjectService/ServerFolderManager.cs
+++ b/ObjectService/ServerFolderManager.cs
@@ -62,7 +62,7 @@ public ServerFolderManager(string rootDirectory)
 		{
 			ObjectIndex = ObjectIndex.LoadOrCreateIndex(indexFile, logger)!;
 		}
-		catch (Exception ex)
+		catch (Exception)
 		{
 			File.Delete(indexFile);
 			ObjectIndex = ObjectIndex.LoadOrCreateIndex(indexFile, logger)!; // try again, recreating the index
diff --git a/Tests/EconomyTests.cs b/Tests/EconomyTests.cs
new file mode 100644
index 00000000..7be415f7
--- /dev/null
+++ b/Tests/EconomyTests.cs
@@ -0,0 +1,96 @@
+using NUnit.Framework;
+
+namespace Definitions.Tests;
+
+[TestFixture]
+public class EconomyTests
+{
+	[Test]
+	public void CalculateCurrencyMultiplicationFactors_Year1900_ReturnsBaseFactors()
+	{
+		// Year 1900 should return base factors (1024 for all indices)
+		var factors = Economy.CalculateCurrencyMultiplicationFactors(1900);
+
+		Assert.That(factors, Has.Length.EqualTo(32));
+		foreach (var factor in factors)
+		{
+			Assert.That(factor, Is.EqualTo(1024));
+		}
+	}
+
+	[Test]
+	public void CalculateCurrencyMultiplicationFactors_YearBefore1900_ReturnsSameAs1900()
+	{
+		// Years before 1900 should be treated as 1900
+		var factors1800 = Economy.CalculateCurrencyMultiplicationFactors(1800);
+		var factors1900 = Economy.CalculateCurrencyMultiplicationFactors(1900);
+
+		Assert.That(factors1800, Is.EqualTo(factors1900));
+	}
+
+	[Test]
+	public void CalculateCurrencyMultiplicationFactors_Year1901_HasInflation()
+	{
+		// Year 1901 should have inflation applied (12 months)
+		var factors = Economy.CalculateCurrencyMultiplicationFactors(1901);
+
+		Assert.That(factors, Has.Length.EqualTo(32));
+		// All factors should be greater than base value due to inflation
+		foreach (var factor in factors)
+		{
+			Assert.That(factor, Is.GreaterThan(1024));
+		}
+	}
+
+	[Test]
+	public void CalculateCurrencyMultiplicationFactors_Year2030_ClampsCorrectly()
+	{
+		// Year 2030 is the max, so 2031 should be treated as 2030
+		var factors2030 = Economy.CalculateCurrencyMultiplicationFactors(2030);
+		var factors2031 = Economy.CalculateCurrencyMultiplicationFactors(2031);
+
+		Assert.That(factors2031, Is.EqualTo(factors2030));
+	}
+
+	[Test]
+	public void GetInflationAdjustedCost_Year1900_ReturnsBaseCost()
+	{
+		// For year 1900, with factor 1024 and divisor 10, we should get:
+		// cost = (100 * 1024) / (1 << 10) = 102400 / 1024 = 100
+		var cost = Economy.GetInflationAdjustedCost(100, 0, 1900, 10);
+		Assert.That(cost, Is.EqualTo(100));
+	}
+
+	[Test]
+	public void GetInflationAdjustedCost_Year1901_HasHigherCost()
+	{
+		// For year 1901, cost should be higher than year 1900 due to inflation
+		var cost1900 = Economy.GetInflationAdjustedCost(100, 0, 1900, 10);
+		var cost1901 = Economy.GetInflationAdjustedCost(100, 0, 1901, 10);
+
+		Assert.That(cost1901, Is.GreaterThan(cost1900));
+	}
+
+	[Test]
+	public void GetInflationAdjustedCost_NegativeFactor_ReturnsNegativeCost()
+	{
+		// Sell costs use negative factors
+		var cost = Economy.GetInflationAdjustedCost(-50, 0, 1900, 10);
+		Assert.That(cost, Is.LessThan(0));
+		Assert.That(cost, Is.EqualTo(-50));
+	}
+
+	[Test]
+	public void GetInflationAdjustedCost_InvalidCostIndex_ThrowsException()
+	{
+		_ = Assert.Throws<ArgumentOutOfRangeException>(() =>
+			Economy.GetInflationAdjustedCost(100, 32, 1900, 10));
+	}
+
+	[Test]
+	public void GetInflationAdjustedCost_InvalidDivisor_ThrowsException()
+	{
+		_ = Assert.Throws<ArgumentOutOfRangeException>(() =>
+			Economy.GetInflationAdjustedCost(100, 0, 1900, 63));
+	}
+}