I have been interested in getting into this hobby for a long while, and not 'till last night while watching Myth Busters was I compelled to finally get into the hobby.

I've done some research and for the most part the hobby seems sort of expensive. I leave for Parris Island June 11th so I don't have a lot of time to fly. Since that's the case I was thinking this plane here:
http://www.nitroplanes.com/j3pipercub.html
http://www.nitroplanes.com/sldieprtf.html
http://www.nitroplanes.com/supersonic.html

I would like to spend no more then $75

Are these some good choices? What would you recommend?

Thanks,
aust10n