A price for a project like that may vary depending on many aspects, actually - from its simplicity and geo to such things as target audience (their ability to pay) and a specifics of a chosen niche. For example, if it's an app for calculating calories, al you ned to do is to consider a huge database with many details. But if you're going to work on a monitoring project like the one described
here, it will require a profound research, competence in how different devices work, and many other things :moil:
Or, if you have a close friend who is ready to help you with an app development being driven by an enthusiasm only, you'll definitely pay less xd
So, there are quite a lot of options actually *sigh*