In places like Milan station, you'll find a few, it all depends. Some stores have more than others. But the plus side is in places such as Causeway Bay, there are many of these resellers shops within walking distance of one another. There's Milan Station, Vip Station, Paris Station (haha I know their names are quite funny). But in these shops, you'll find mostly LV and Hermes.
If you have any local friends who has something called a Joyce card, bring them along with you to Joyce or the Balenciaga store in Central. You'll get 10% off normal merchandise including bbags.