diff -r e7d15ae60d43 -r 91eca6fdee8d src/economy_new.cpp
--- a/src/economy_new.cpp	Sat Mar 31 13:19:30 2007 +0000
+++ b/src/economy_new.cpp	Sun Apr 01 09:38:43 2007 +0000
@@ -119,7 +119,8 @@
 /**
  * Obtains the costs that a certain user operation at a tile would generate.
  * This function takes into account that cost that arise from obtaining ownership
- * of the tile in question.
+ * of the tile in question. Note that these costs are not accounted for in the
+ * very simple difficulty levels.
  * @warning         This function needs to be called BEFORE the tile actions
  *                  are performed. Otherwise you'll get an assertion on the command
  *                  because the computed prices for the test and the exec run are
@@ -137,7 +138,7 @@
 {
 	int32 cost = m_prices[operation];
 
-	if (tile == INVALID_TILE) return cost;
+	if (tile == INVALID_TILE || _opt.diff.economic_model == 0) return cost;
 	if (release) cost -= Town::GetTilePrice(tile);
 	else if (_current_player < MAX_PLAYERS && _current_player != GetTileOwner(tile)) cost += Town::GetTilePrice(tile);