In the past few weeks different people came to me with the dreaded phrase: "I have an idea for an app". If you feel targeted, you probably are, but you're not the first, and you won't be the last. Some even trusted me enough to tell me what their great idea was. Many, though not all, couldn't code their way through a paper bag and thus they look for someone "to code the app for free".
You even might find someone like that, and if you do, it's someone with a lot of time on their hands like a student with not much experience.
What those ideas (if I get to hear them) all have in common is that they need infrastructure behind it. Uploading pictures, movies, heck, even simple text need a place to be stored. That's definitely not your phone, especially if others need to be able to access it. Yeah, you can start off with hosting a little database and web front end on your DSL line (if you have one), but in the long run this will require some serious money.
I'm not even talking about the people managing and creating it for you. I'm just talking about bandwidth, storage, electricity.
So, if you have an app idea, assess where you want to store what: if you have no concrete answers to those questions, shelve your idea until you do.. An app is nothing magical, it requires real resources, real work and thus real money.