Just out of curiosity, how does your battery app make $50 a month?
EDIT: Just finished reading the whole thing and I have some additional questions:
You don't talk much about customer development, at least not directly. Does this mean that in your experience you've found that reviews in the App Store are a good enough proxy for soliciting customer feedback? Or did you just leave that part out for one reason or another?
Feedback isn't something I've really had to work for. I have contact forms on my websites which people get to from the support link in the app store, and I've put my email in some of the apps. In addition to the reviews I also get emails whenever somebody has a suggestion or a problem.
If you have something really broken it will show up in the reviews pretty quickly, otherwise plenty of people email me letting me know what they'd like to see in future updates.
If you are asking in general, I have no idea. lol. If you are asking specific monetization there is a paid app for .99 and a free app with ads in it. Most of that is from the ads in the free app.
If I wanted to I could probably redo the graphics now and actually make significantly more. There are a few apps that do the same thing that make some real money. I just did this a test when I was first learning about the app store and I don't find it to be interesting so haven't put any time or money into it. I just find it interesting that it still gets downloaded every day and makes enough money in a month for a decent meal :-)
EDIT: Just finished reading the whole thing and I have some additional questions:
You don't talk much about customer development, at least not directly. Does this mean that in your experience you've found that reviews in the App Store are a good enough proxy for soliciting customer feedback? Or did you just leave that part out for one reason or another?