Black market: elite shop for expensive goods, private sellers, weekly catalog value ~20k

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

src/Decentralized/BlackDelivery.cs

@@ -20,12 +20,15 @@ namespace Decentralized
             ModHook.OnGenerateCustomerNormal -= OnGenerate;
         }
 
+        private static readonly System.Collections.Generic.Dictionary<string, long> ValueCache = new System.Collections.Generic.Dictionary<string, long>();
+
         public static long Value(string id)
         {
+            if (ValueCache.TryGetValue(id, out var cached)) return cached;
             var it = ModHelper.SpawnItem(id);
-            if (it == null) return 0;
-            long v = it.GetBaseValue();
-            it.Destroy();
+            long v = 0;
+            if (it != null) { v = it.GetBaseValue(); it.Destroy(); }
+            ValueCache[id] = v;
             return v;
         }