Informant

Informant displays additional information about items in their tooltips: buy price; sell price; item level; what quests, classes or professions use the item; the value of the item produced by a recipe; etc. Informant can also tell you what vendors sell a given item.

This is a Standalone addon it was previously integrated into Auctioneer but auctioneer never got an update on cata_classic after the AH update.

Requirements:

It needs another addon "stubby"