I also found a few stacks of Cobalt Ore in the auction house for about 40g a stack, so I bought and smelted them aswell. I've listed them 300g each stack and 4 of them have already sold! Should make the duration only 12 hours because it's common trade goods so people will undercut you at some point.
There's 2 good places to farm in my opinion. Howling Fjord and Zul'drak. I tend to find the most from Howling Fjord, but many people say the opposing. Maybe it's the route you have to use.
I use the following path myself for Cobalt farming. You can create a path too with Routes and Gathermate2 addons. You should also add treasure chests and other points of interest to the route. They may contain something valuable! If you don't know how to setup a route, leave a comment and I will add a small how-to.
Saronite and Titanium Ore should be farmed in the high-end zones, like Icecrown Glacier or Storm peaks.
There's also some very good items you can create from Saronite and Cobalt that will give even more profit, but more on that later!
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