How about Kangmeile Sports Fitness Club Peking University Branch?
Biennial card, unlimited times, 900/ person. Very cheap. The location is the first floor below the Science Building in Peking University. Because it is underground, the air can't be so fresh, but it makes sense. This place is neither too big nor too small. There are 20 treadmills and fitness machines, but you can find the one you want to exercise. There is also an article on the training ground of taekwondo and yoga, which is quite big and looks good. 900-year-old card, the coach customizes the fitness plan for you free of charge, which is very humanized. Although often because of time and laziness, I can't make it to the end ~ but at this price, I really can't find a second facility in Beijing. I like it. !