Hello. I'm new to the forums but i have been reading them for about 2 weeks.. I think that this morning i figured out how to edit personal things the vendors sell.. I could give you a long story about how i figured this out...........but who cares? Here is a step by step guide;
1) Open up your WoW directory. Located in C:\Program Files\Worldofwarcraft.
2)There will be a folder called WBD. Open it.
3)In side are some files. We will only concentrate on two of them.
4)Open up the one named 'itemcache'.
5)Now open up the one called 'itemnamecache'.
6)If you search around in the 'itemcache' one you will find something that is sold by a vendor of some sort.
7)Now go get an item from the 'itemnamecache' that you want the Vendor to sell.
Now replace the item you found in 'itemcache' with your new item. You must write it as many times as the previous item was written down.
9)Save both files and close all the windows down.
10)Run WoW find the vendor that you were editing and then where he would normally sell 'Normal Item Here' he will now have 'Item that was Replacement here'.
Enjoy!
NOTE: I have only tested this once so it may only work with certain items. I'm not sure. Also Vendors that sell the same item as you replaced will still sell that. You have to find the right one. This can take quite a bit of time.. It took me 8 hours to find the right vendor. He was in Kalimdor!