Is a pretty good post on the costs / timescales for developing an iPhone app. The TL;DR version:
- An iPhone developer costs $200 - $1000 an hour - obviously cheaper developers will take longer so it'll even out and you'll likely end up with something worse. (This seems high but it tallies with other figures I've seen)
- All in a good developer would likely need about 2 months elapsed time to get a good app to a shippable state
- The likely cost is therefore about $100,000 to $150,000. The absolute minimum he thinks is feasible is around $30,000. (He assumes only half the time he might spend is chargeable if you're questioning the calculations).
There was another really good article on the over revenue which I can't find now but essentially it boiled down to:
- There are plenty of stories of people spending a few hours on an app and making thousands but again, these aren't typical.
- The majorly profitable apps make the headlines but they are not the norm.
- The average application does not even come close to covering it's costs at commercial rates (see above) therefore the ROI is negative.
I can't remember the precise figure but the number of apps which are profitable at commercial rates (that is paying for the development rather than doing it as a hobby) was less than 20%. I'll try and dig it out.
Here's another interest piece (actually a reddit Q&A) from a guy who has developed for both iPhone and Android:
P.S. Spend is a cracking application. I use it all the time - the paid version (59p - woo).