Mithril is your Cabal Alz maker. Engineering and Blacksmithing both need massive quantities of the stuff, and it sells fast, and for a fairly high price. One word: Tanaris. You could travel around the whole thing, but Ive found it much easier to start at Gadgetzan, and cut across the desert to the start of the bug area, checking all of the little rock outcroppings on the way.
This place is dangerous, and I even die some at 45+, but there are alot of spawns here. Travel along the edge, and then back along the outter boundary of it, and then continue on circling the map. There are a lot of Cabal Online Alz in here, and their value shows in the defense the mobs put up. Im not going to lie to you, itll be hard to live consistantly here without a mount or travel form. Thistle shrub valley also has a few, and then another bug area on the edge of UnGoro crater. There are also one or two by ZulFarrak and the area close to Gadgetzan. They do not spawn as often as the others do, though.