App Development

We need an app developed for a non profit organisation (for those who suffer with chronic pain/fatigue) for android market. Consisting of some info pages (written by us), a diary for input of pain and energy scores out of 10 & for input of private/public notes, a calendar with the ability to input medication for reminders, a forum, member profiles with the ability to update status'/posts, and to talk to/message each other and to add members as friends. Here is our website The Administrator removed this message for containing contact details which breaches our Terms of Service We have the idea's, layout and designs already done, but don't know how to code/make an app. We only have £50, how much would this app build cost please?