Sim Lim Square, like many downtown shopping centers in Singapore, has quite a lot of photo shops and, if you are a good haggler, can be quite reasonable, even by U.S. standards. HOWEVER, you really need to be honest with yourself as to whether or not you are a good haggler...some of the shops are *masters* at luring you in with a great price on a body (for example) and then, before you know it, you've purchased innumerable extras at probably exorbitant prices, negating the great price you got on the body (yes, this is a true story, and yes, it is my story).
Anywho, Sim Lim great if you're up to it. If you simply want a straight deal and a good quality store to back it up if you ever have problems, then go to Parisilk in Holland Village.
Rig: 50D Tamron 28-75 2.8 Canon 50 1.4 Canon S 10-22 550EX Elinchrom D-Lite 4 Oh yeah, and one a'them 70-200L 2.8, too!