McGill Gym summer membership is still on promtion, $99 for 4 monthes. There are six badminton courts over there and the official time slots for badminton are Thursday 18:30 - 20:30, Friday 18:30 - 20:30 and Sunday 13:00 - 17:00. Moreover, since many time slots are empty, I don't think it will be a problem to use them to play badminton.