WARNING: THIS IS VERY VERY SIMPLE!!!
Ok, I am sure lots of people know this, but just for those who don't, this will be pretty useful to you in YOUR server. (If you wanna make blizzard Tiers or anything.)
Ok, so inside the world DB, there is a section for items_extendedcost
It looks a little something like this
Ok see it there, now I'm gunna explain the columns.
1st Column looks like this:
This column is where you type in the item that you want to sell. So say you want to sell your New Tier 7 head piece for a token that people get off drops, then you enter the ENTRY ID of the head piece in column 1.
2nd Column looks like this:
This column is for the token. Just put in the ENTRY ID of the thing that you want your item to cost. (In this case its the token) Simple enough, no?