I've also heard Cathay is the place to go. But in general, I find the purchasing experience in Singapore to be a bit frustrating, as I'm not as accustomed to it. I spend a few weeks a year in Singapore and I've never bought any camera gear there.
First of all, some of the places in certain areas are big on bargaining. I know what I can get a lens for in the US and Japan, and I really don't like spending the time to see what price someone wants in Singapore.
Second, while this hasn't happened to me, I've been warned that there are less than honorable places that quote you a price without the extras (cables/chargers, etc) that are supposed to be included.
Third, the Singapore photographers I know tend to buy their stuff in Hong Kong, which is a sign to me that Singapore isn't going to be price favorable for me.
What I do know is that the used market in Singapore seems to be considerably cheaper than US used markets (ClubSnap forum). But the condition of the gear does need to be looked at very carefully, as it's a humid area and fungus and dry box storage may be a concern.