Make sure of one thing first, though. If you're hiring a real developer, not someone who's going to give you an app he knows of, maybe with the developer's name removed and the app renamed, have a lot of money. Software developers don't do one-offs cheaply. If you sell 50,000 copies of an app (and some apps in Play have sold in the hundreds of thousands) for $1 net each, you've made decent money. If you're making it for one person, you're going to charge the same amount. But one person, you, will be paying it. (Developers earn around $50/hour and up - and if the app is complex enough it can take weeks to develop, test, debug, etc. That's $2,000/week and up - and no profit added in yet.)