I trained MMA for a short while during the holidays, but I started working. I'm looking to get back into it some time soon. It was fairly cheap for me, you could join the gym the fight team trained at and the training was free, or you could just pay £4.00 a session.
Anyway, if you want to train MMA try and find a gym that is specific for MMA that train all aspects, Wrestling, Muay Thai, BJJ, Conditioning etc, then I suggest that you do that. Don't go and train at 2-3 seperate gyms, one doing BJJ, one doing MT and so on.
All so, if you are still at school, try and join the wrestling team, we have nothing like that over here but it's a real good base, a lot of real successfull MMA fighters have come from being straight wrestlers and learning the other bits and pieces like Couture, Hughes, Koscheck, Coleman (Not learned too much of the other thing, but still

) and a lot of others. Rich Franklin has said he wished he joined his HS wrestling team when he was at school.
Good luck mate and keep us updated.