I vote for soccer! It's a pretty cheap sport, easily accessible (there are not many hip hop classes and there are more soccer fields than pools around), teaches you to cooperate with people, the gear is minimal, and there are different teams for different levels. Best thing though--running around in fresh air--and it's a sport that can be played year around (indoor for the winter). I have to say I owe my life to soccer for keeping me out of too much trouble growing up (and even as an early adult).
Just my .02