Index: C:/Development/l2j/eclipse/workspace/L2_GameServer/java/net/sf/l2j/gameserver/clientpackets/RequestBuyItem.java
===================================================================
--- C:/Development/l2j/eclipse/workspace/L2_GameServer/java/net/sf/l2j/gameserver/clientpackets/RequestBuyItem.java	(revision 1247)
+++ C:/Development/l2j/eclipse/workspace/L2_GameServer/java/net/sf/l2j/gameserver/clientpackets/RequestBuyItem.java	(working copy)
@@ -94,10 +94,15 @@
 	{
 		L2PcInstance activeChar = getClient().getActiveChar();
 		L2FolkInstance folk = activeChar.getLastFolkNPC();
-		if (!(folk instanceof L2MerchantInstance) || activeChar.getDistance(folk.getX(), folk.getY()) > L2NpcInstance.INTERACTION_DISTANCE)
-			return;
+		if ((folk instanceof L2MerchantInstance) && activeChar.getDistance(folk.getX(), folk.getY()) > L2NpcInstance.INTERACTION_DISTANCE)
+		    return; // If talking to a merchant and too far
+		else if (!(folk instanceof L2MerchantInstance) && !activeChar.isGM())
+			return; // If not talking to a merchant and not a gm (gm shop)
 
-		L2MerchantInstance merchant = (L2MerchantInstance)folk;
+		L2MerchantInstance merchant = null;
+		// prevent cast exception and allow GMs use gmshop
+		if (folk instanceof L2MerchantInstance)
+		    merchant = (L2MerchantInstance)folk;
 
         if (_listId > 1000000) // lease
 		{
@@ -138,7 +143,7 @@
 		int tax = 0;
 		double taxRate = 0;
 		
-		if (merchant.getCastle() != null)
+		if (merchant != null && merchant.getCastle() != null)
 		    taxRate = merchant.getCastle().getTaxRate();
 
 		for (int i = 0; i < items.size(); i++)
@@ -241,7 +246,7 @@
 		}
 		
 		// Add tax to castle treasury if not owned by npc clan
-		if (merchant.getCastle() != null && merchant.getCastle().getOwnerId() > 0)
+		if (merchant != null && merchant.getCastle() != null && merchant.getCastle().getOwnerId() > 0)
 		    merchant.getCastle().addToTreasury(tax);
 
 		//TODO only send Inventory update instead of full list !