Good luck on that one. I pulled in one of their trainers for some Spanish to English translations and I could tell he was embarrassed by how I was treated. I could tell he was a good guy and I asked his opinion of the pricings and he merely said "I'm a trainer and don't control the pricings'. Nevertheless, the gringo will be charged more, you just have to accept it as I did b/c I really liked the gym. i hear good things about Sportclub, Wellsport and one more that is kinda new that has a pool and aerobic classes outside that seem to be price competitive. I recommend you ask for the different plans (silver, gold, plat, etc) b/c you will be automatically signed up for the platinum one.
Sal - the porteno I know who pays that amount can only go to R-Pena and Belgrano locations - the older ones. Still, the prices we pay will be alot higher.