I used to go to Oasis gym and I just pay 250 monthly but I don't know how much now. And you still have the option to swim right after your gym session. Or you can go to Rydges Hotel there is a gym there at the roof top, last time I went there it cost me Qr. 1100 in three months, its money's worth to go there. The instructors are very friendly and the service is good, they also have a sauna bath included in the gym package.