I spent $500 dollars trying out 10 different traffic sources to scale horizontal running an offer for mobile CPI over at AppFlood [sign up here] Many gurus out there say, if you have a winning campaign you can just cut n paste it to other traffic sources and you will be stacking that money.
I wanted to put that “simple and easy cut n paste method” to the test , so I took one of my killer, strong campaigns where i spent high xxxx on data, and had optimized on my favorite traffic source and decided to load up $50 bucks into 10 different traffic sources and bid everywhere the minimum CPM or CPC they require. Now on some traffic sources this was $2.50 CPM, on others 0.05 CPC, and so on so forth.

I do a lot of Pay Per Call on mobile lately and use the top 290+ cities in America. This list was taken from Wikipedia, but I cleaned it up, removed all the junk and giving you nothing but a sexy list you can cut n paste and use right away wherever needed.