This site also has a good list. In the column to the left go to Trade Skills -> by Trade -> Leatherworking. There should be links telling you where each recipe can be aquired. Normally a recipe with colored letters is a drop and white letters means you can get it from a vendor somewhere (there are exceptions, but this is the general rule).
I strongly recommend looking up any recipe before buying it at the AH. There are folks who do nothing but camp vendors and resell recipes for an often obscene profit. There's no rule against this, of course, but personally, I don't like them and refuse to let them have my money if I can find any way to avoid it.
When I see a recipe I want at the AH, I immediately plug the name of it into the big white box on Allakhazam's main page and look it up. Saves me loads of time, money and hassle.