It goes without saying that the highest quality reps are available from the dealers here, and that 'going solo' brings risks in quality. That said, the fun can be in the shopping and the haggling - plus you don't have to worry about shipping (customs may be looking for bling when you land though!)
I really enjoy shopping in the Hong Kong markets, even if it is a tourist trap (they saw you coming!). I agree that Mong Kok / northern end of Kowloon is a good place to wander.
In the past I've found that to get the real reps you end up being taken up godforsaken alleys into some grotty buildings, a steel door opens up on the fifth floor and suddenly you're in a rep sweatshop. That was pre-1997, but in this day and age I assume the reps just come in from China.
Which brings me to the best place to go 'fake' shopping - over the border in Shenzhen, if you fancy a day trip. The sale of ripped off stuff is blatant there. They will even fake Cisco routers....
Not sure this helps all that much, but it might point you in the right direction. Enjoy!