I've worked at Backflip for the last year. The company was started by a few friends of mine from a previous startup here in the Boulder area, and since then it has grown from 6 fulltime employees to 10. We're growing at a good rate and are still looking for great engineers (hint hint).
The amount of money we spend making a game for iOS or Android varies a lot depending on the scope of the project. A game like Paper Toss or Strike Knight is primarily art bound, so if you have a great in-house artist or two (we do) then you can figure out the cost based on 1-2 months of dev time for one engineer, 1 month for art, a few weeks for sound, and a few weeks for random QA/marketing/etc at whatever pay rate is applicable to your area. If you need to replace any of those components with contractors, your cost will definitely increase.
Anyone with insights into Backflip Studios? Number of people working full time, how much money spent building this range of games?