I had an addon that told you the merchant price of quest rewards and I lost it in a format. Does anyone know of the addon that does this?

I would deffently go for www.wowecon.com it update and tells you price of AH and stuff - try it out .

Auctioneer worth a look...

Cola Light from wowace.com will do this.

Auctioneer's Informant for prices (especially if you think about using Auctioneer anyway) + ItemDataCache for price updates.

the addon i was using had the price a NPC would pay for the loot before even if i havnt sold that item before.

Informant knows lots of items for start, as well as IDC, with both of them you'd cover 99% quest rewards. Updates are just a very nice extra.