$2-5k per month (after Apple's cut) from my Fitbit mobile app, Fitwatchr: https://itunes.apple.com/us/app/fitwatchr/id684005201?mt=8&i.... The unique value is Fitbit activity conversion to Weight Watchers points as well as a tougher but more rewarding calorie tracking that is based on real science (Mifflin equation). Effort on my part really depends on me/my current schedule as it's a side project. I admittedly have some bad reviews that boil down to getting users to understand how the calorie tracking works. Using Freshdesk (love it!) to answer 1-2 emails per day. It'll be 1 year working on this next month.
That's quite a good revenue. Is it only from app sales ?
I've checked on App Annie ans your app seems to be around 500 (grossing) in health & fitness in the US. I find it a bit surprising that there are 500 apps in health alone making >2k month.
Yes, only app sales - no IAP. Not sure how to explain other apps, but if you look at the list of top paid Fitness ones, many of them charge more than the typical 99 cents - that probably factors into it. It certainly does for mine! Also, I've noticed Yoga, pregnancy, etc apps absolutely kill it (consistently!) in sales day after day after day....
Unfortunately for the first version I didn't track hours (I am now). It took all of last summer (June to August) of nights and weekends. Not too bad considering it was only a few hours per week b/c of being more active outside due to Summer. It's PhoneGap based, so much of the effort wasn't so much writing features so much as learning/figuring out the tools I used: KendoUI Mobile for the UI, PhoneGap Build for building native versions, and Knockout.js. I come from a .NET backend background, so I wanted the new challenge of building an app with frontend tech, not only for CSS/JavaScript practice but also benefiting from one codebase for multiple platforms (iOS, Android, and WinPhone 8).
