ive noticed you can change the items in a shop to buy but the item will not buy...
either:
1) NPC will only sell what they got on offer, so you can change postions of the item in a shop and it works, but change the item and it wont
2) There is a trigger that says if a item if buyable or not.....
01 A9 00 , is DB code in ITem Table, goto shop.dat and change DC 2C 00 to 00 9A 10
and look at green dye, its not a DragonBall, Price 10000 to buy, but you cant buy it it wont work....
is it possible to buy or, you think each NPC ,server side has a set of items you can buy and each item is set to a number, so even if you chang the item it has a diffrent number sothe server will not reconise it..... anyway just a idea