Occasionally while shooting at events, people would ask me where to go shopping for camera gears. I've compiled a list of local stores where you can find majority of the well-known brands for both photo / video equipments and accessories.
You can read this thread on the Clubsnap photography forum for reviews of the various retailers. It's unlikely to get ripped off from these stores, but please do some resarch first on what you want to buy and do not be sweet-talked by the salesman for something else. And remember, keep the receipt for warranty claims, as an unfilled warranty card is of no use for such purpose.
Be sure to read up on avoiding the Singapore tourist traps if it's your first time here. Enjoy shopping!