best place i find personally is here actually... or Singnet Classifieds. the camera dealers tend to be more expensive (they have to be, otherwise how to make profit), but as long as you know what to look out for, getting from other photogs is usually ok.
Its the building next to Funan IT Mall, behind Excelsior Hotel, opposite Adelphi. Camera Workshop is located on the ground floor, diagonally opposite Ruby. If you're not sure, try to join one of those future SEED and I'm sure some of those guys will point you in the right direction.