As TheFlyingCamera said, Cathay is a great shop in Singapore and Peninsula Plaza, and shops on the the other corners of the junction, are the place to head for photography. I always do and am always impressed with myself when I come away without having bought anything! That said I don't remember ever having seen a LF camera, not to say they are not there somewhere.
Do also check out Ruby, across the road from Cathy and THE place for all your film and paper and chemical supplies (Cathy have given up and replaced all that stuff with a couple of inkjet printers). Never seen a LF camera there either but their website says they have them. Certainly very friendly if you email them.
rubyphoto.com.sg
Welcome in advance if you are coming up here to KL as well. Unfortunately I've never seen a LF camera here either, although I did see a pack of 4x5 film for sale the other day, so someone's got to have one somewhere. The Malaysian forum to visit to find more informed information is
photomalaysia.com
If you do track down what you want, with regard to prices, Cathy will quote you in advance by email, but take the email with you when you go. In Malaysia no price on a sticker is the real price, even in the flashiest of shops expect to get at least 10% off.
Sorry I couldn't be more direct help but do enjoy your visit to these parts,
Hywel