I am looking for (if one is made) Of an addon that you put in say soul dust and it will scan auction for everything that will disenchant to that item. and set up so you can buy those items (be nice if had an auto bidder added)  Anyone heard of this addon??  Or thinking about building one?

Enchantrix, which you can get seperately or part of Auctioneer, has a disenchant predictor. Hooks the information right into the tool tip, so when you mouse over an item, it tells you the most likely mats it will disenchant into.

myrroddin you must get lots and lots of chocolate cake ^_^

Plus if you know what lvl an item has to be like say Soul Dust can be deenchanted from common items lvl 30-35 -which is a part of the GFW Disenchant Pridictor.  You can also just search the AH that way.