I agree with drauk on this. The major problem with doing it yourself is the time it's going to take. I know because I'm in the middle of doing a similar project. It seems that everyday you bump into another little problem that requires research and experimentation to resolve. Great fun if you are into that sort of thing but a pain in the butt otherwise.
To save costs I've got a cheap old PC running Linux to do all the development on, so I'm not paying for server rental at this time. This means having to learn Linux for the operating system, Apache for the web server, MySQL for the database, C++ for server side processing (I'm a sucker for punishment!), Javascript for any client side processing, the list goes on. But that's the kind of thing I enjoy.
Regards
Stoney