A byword for all that is cut price and geeky, Sim Lim is jammed with stalls selling laptops, cameras, soundcards and games consoles. If you know what you're doing, there are deals to be had, but the untutored are likely to be out of their depth. Bargain hard (yet politely) and always check that the warranty is valid in your home country.
Sim Lim Square
Little India & Kampong Glam