You will have to go through the spiel. There is not one price and everyone pays something different. You pay more for a shorter contract and less for a longer one - which obviously depends on how long you think you might be here! You also pay more for use of ALL the gyms and less just one gym - so depends on where you live and whether you want to go to one close to work, close to home, both, or also while in Singapore, Malaysia etc etc....
Finally, if you are really strapped for cash I think you can get memberships just for certain times of day (offpeak).
So ... it all depends. Those guys are negotiators though - keep strong and have a clear view what you want before you go in....
I think you might also get a discount for paying with an HSBC credit card (but that might just have been a negotiating ploy too!)