I'm talking about the really popular ones - Angry Birds, Candy Crush, Bejeweled Blitz, etc.
I'm guessing 100 to 250k, but that's just a wild stab in the dark.
Googling that info is really tough and the top estimate I've seen for any apps is 250k.
3:02 pm on Jul 1, 2013 (gmt 0)
Lots of reading can be found on this topic, no doubt. Angry Birds took like 8 months. You can find quite a bit on their own site, but here is a news article from last year that may provide some insight as to the process, expectations and unexpected/unforeseen issues.
Many apps have heavy backend, which creates huge costs. For example, the famous Viber (Telecom app), developed by our teams in Belarus, takes a solid group of engineers just to do regular support. There are also mobile apps for enterprises, which require linking with SAP or other corporate systems and may easily cost $1 mln.