score:6
The easiest option is almost certainly the nearest supermarket, but if you're looking for something a little more tarted up and are willing to pay the corresponding premium, you could do worse than Regency Spices. They've got a 14-piece "Chinese Spices Starter Kit" (HKD 328, ~US$42) and will even ship it worldwide for an extra $9.
Response to an e-mail asking if I could purchase directly at their address or order and collect there:
You can do both at the same address! It may be easiest to order online for pickup as we pack and grind fresh, depending on what you're looking for some of our products take a while to prepare.