The night market near Temple Street is chocablock full of fakes (branded t-shirts, caps, watches etc) if that's your bag. You'll also pick up souvenirs and nic nacs for a fraction of the price that you'd pay at, say, at Victoria Peak. The night market is extremely cheap. You can take the metro to Yau Ma Tei and walk back through the market towards the 'centre'/harbour area.
CDs are much cheaper in HK too (as you probably know a lot of CD Wow's stock ships from HK).
As mentioned good bargains on electronics/electrical can be found once you know what you're after.
And there's a monsterous shopping centre on the HK island called Times Square - something like 9 floors of shops.