When I lived in Singapore I used to get my games from Lucky Plaza (if you know where to look)... best thing to do is make a trip to JB and buy all your games for bargain prices.
I'm sure if you look around you'll be able to find a copy, Tampinese Mall usually has a great gaming store on one of the higher floors... again, this is when I used to live there, I've been out of Singapore since 2003 so I don't really know how much has changed.