Tricky question, but instead of writing a long post about it, I will try to summarize the factors that decide the cost of an app:
1. Innovation needed ? More innovation, more creativity is needed from a group of people? You should expect to close a good funding round in the range of $500k and get a set of brilliant people under the roof for a year or 2.
2. Pure Volume and amount of work to be done on the app A.K.A features.
3. The length of contract, developer teams tend to charge less for a longer contract commitment.
4. Whether you need local developers or not : Same app can cost about $100k for 4 months of MVP launch in U.S, when compared to getting it developed for $20k with a good development team in India.
5. Whether you have a business plan (yes you heard me). If you have a business plan, that means you are serious about your business. It means you want your team to develop processes, documentation, specification etc etc, that takes as much as time it takes for development. So you have to decide what you are trying to do and whether you know how exactly you will achieve your goals.
6. Enterprise apps are completely different ball game, can because of the nature of the scope and dedicated teams needed to develop such a business, it can cost in range of early to high six figures.
7. If you are a startup looking for a mobile app development team, then you should look for small teams who work on their own startups. Think about it, do you really want to hire a boutique agency who claims they have worked with Google or Samsung or do you really need quality team who can hit the ground running for you and do what you would for your business?
Hope that helps and you guys have a great Wednesday!