it makes more sense to call them "YahooAuctionsItem"s rather than "Listing"s because i always use variable names like "item" or "SelectedItem" for them

Listing.cs

@@ -5,7 +5,7 @@ using System.Collections.Generic;
 using System.Text.Json;
 
 namespace Buypeeb {
-	class Listing {
+	class YahooAuctionsItem {
 		public string url {
 			get {
 				return $"https://page.auctions.yahoo.co.jp/jp/auction/{this.id}";
@@ -31,13 +31,13 @@ namespace Buypeeb {
 
 		private bool success { get; set; } // TODO: custom setter that throws an exception if set to false or something idk
 
-		public Listing(string id, string name) {
+		public YahooAuctionsItem(string id, string name) {
 			this.id = id;
 			this.name = name;
 			this.ready = false;
 		}
 
-		public Listing() {
+		public YahooAuctionsItem() {
 			// parameterless constructor for deserialisation
 		}
 

MainWindow.cs

@@ -52,10 +52,10 @@ namespace Buypeeb {
 
 		static SemaphoreSlim tasklimit = new SemaphoreSlim(4);
 
-		private Listing SelectedItem {
+		private YahooAuctionsItem SelectedItem {
 			get {
 				this.itemTreeView.Selection.GetSelected(out TreeIter iter);
-				return (Listing)this.itemTreeView.Model.GetValue(iter, 0);
+				return (YahooAuctionsItem)this.itemTreeView.Model.GetValue(iter, 0);
 			}
 		}
 
@@ -97,7 +97,7 @@ namespace Buypeeb {
 
 			// bind treeview columns to watchlist instead of needing to manually sync its liststore
 			this.itemTreeView = (TreeView)builder.GetObject("TreeViewItems");
-			this.items = new ListStore(typeof(Listing));
+			this.items = new ListStore(typeof(YahooAuctionsItem));
 			this.RenderList();
 
 			this.itemTreeView.Model = this.items;
@@ -136,7 +136,7 @@ namespace Buypeeb {
 			this.itemTreeView.Model.GetIterFirst(out iter);
 
 			for (int i = 0; i < this.itemTreeView.Model.IterNChildren(); i++) {
-				var x = (Listing)this.itemTreeView.Model.GetValue(iter, 0);
+				var x = (YahooAuctionsItem)this.itemTreeView.Model.GetValue(iter, 0);
 				if (x.id == id) {
 					return (this.itemTreeView.Model.GetPath(iter), iter);
 				}
@@ -413,22 +413,22 @@ namespace Buypeeb {
 		// column renderers
 
 		private void RenderColumnName(Gtk.TreeViewColumn column, Gtk.CellRenderer cell, Gtk.ITreeModel model, Gtk.TreeIter iter) {
-			Listing item = (Listing)model.GetValue(iter, 0);
+			YahooAuctionsItem item = (YahooAuctionsItem)model.GetValue(iter, 0);
 			(cell as Gtk.CellRendererText).Text = item.name ?? "Loading...";
 		}
 
 		private void RenderColumnPriceYen(Gtk.TreeViewColumn column, Gtk.CellRenderer cell, Gtk.ITreeModel model, Gtk.TreeIter iter) {
-			Listing item = (Listing)model.GetValue(iter, 0);
+			YahooAuctionsItem item = (YahooAuctionsItem)model.GetValue(iter, 0);
 			(cell as Gtk.CellRendererText).Text = item.ready ? item.PriceJPY() : "...";
 		}
 
 		private void RenderColumnPriceAUD(Gtk.TreeViewColumn column, Gtk.CellRenderer cell, Gtk.ITreeModel model, Gtk.TreeIter iter) {
-			Listing item = (Listing)model.GetValue(iter, 0);
+			YahooAuctionsItem item = (YahooAuctionsItem)model.GetValue(iter, 0);
 			(cell as Gtk.CellRendererText).Text = item.ready ? item.PriceAUD() : "...";
 		}
 
 		private void RenderColumnEnding(Gtk.TreeViewColumn column, Gtk.CellRenderer cell, Gtk.ITreeModel model, Gtk.TreeIter iter) {
-			Listing item = (Listing)model.GetValue(iter, 0);
+			YahooAuctionsItem item = (YahooAuctionsItem)model.GetValue(iter, 0);
 			(cell as Gtk.CellRendererText).Text = item.ready ? "whatever" : "...";
 		}
 

Settings.cs

@@ -9,14 +9,14 @@ namespace Buypeeb {
 		public int updateIntervalCritical { get; set; } = 60;
 		public int favouriteUpdateIntervalCritical { get; set; } = 30;
 
-		public Dictionary<string, Listing> watchlist {
+		public Dictionary<string, YahooAuctionsItem> watchlist {
 			get; set;
 		}
 
 		public Settings() {
 			if (this.watchlist == null) {
 				// either this is the first time the program has been run, or there's something wrong with userdata.json
-				this.watchlist = new Dictionary<string, Listing>();
+				this.watchlist = new Dictionary<string, YahooAuctionsItem>();
 				// this.Watch("https://buypeeb.biz/whatever/k12345", "my thingy");
 				// this.Watch("https://buypeeb.biz/whatever/z09876", "your thingy");
 				// this.Watch("https://buypeeb.biz/whatever/h55555", "our thingy");
@@ -28,10 +28,10 @@ namespace Buypeeb {
 
 		}
 
-		public Listing Watch(string url, string name) {
+		public YahooAuctionsItem Watch(string url, string name) {
 			string id = BuypeebApp.IDFromURL(url);
 			Console.WriteLine(id);
-			this.watchlist[id] = new Listing(id, name);
+			this.watchlist[id] = new YahooAuctionsItem(id, name);
 			return this.watchlist[id];
 		}
 	}