If you want to save some money, you’ll need to arm yourself with some basic knowledge before you go. I can't stress that enough. And the first thing you'll need know is how much things cost. Anecdotally, prices in Hong Kong are 10-15% cheaper than back in the US (this excludes local sales tax in the US, so if you factor that in, you're saving even more). Make a shopping list of all the items you want with a corresponding list of prices from back home.
It's important to note that there's NO sales tax in Hong Kong. So stores with signs saying 'tax free' are false advertising. Bargain hard and don’t get suckered into buying 'extras' for your devices. You may be getting that Digital SLR cheap but you may be paying high mark-ups for the memory card and a camera case for example.
If you do want the peripherals, make sure you know what the asking prices are back home. Also note that quality varies on these items. Some memory cards, for example, are better specced than others.
Apart from cameras and computers, stuff that can be cheaper in Hong Kong includes little peripherals for your computers and laptops (accessory cables, laptop cases, keyboards, RAM etc). Aftermarket brands for Apple such as Moshi are often much cheaper in Hong Kong than they are in the US.
Here are some other things to keep in mind:
