Early in a server economy refined deep rock salt is actually quite expensive. It is needed for one of the two devilsaur pieces and is a 3 day cooldown for leatherworkers. Once Dire Maul patch is released in p2 it is also used for hide of the wild. The price of the salt drops off after that point and then picks up again when naxx comes out, but you can get a stock pile and drop the profession towards phase 3 if you like.