You would be shocked at the weath of knowlage that is aviable to us on Allakhazam, to the left is a list of trainers link, selecting smithing will bring up
http://wow.allakhazam.com/db/skill.html?line=164
clicking on items in the list will help you find who has what for sale. Rember most of the realy cool stuff is not trained, but is found as droped scrolls .