Look at Chupamobile for pre-developed apps with source code:
You can have a scalable Instagram type app with server support in a couple days for a few hundred dollars (note: many still use Parse so need to understand their migration plan).
I had pretty low expectations when I explored this last year. Realistically, what could you get for $399? I was pretty blown away. I branded, customized and integrated an app into our environment in ~ 3 weeks.