One option is to go to one of the 5 Apple Retail Stores in HK. Some people who scored a reservation through IR pick up his phones, ultimately wants to sell it to Sin Tat anyway, therefore flippers camp outside to buy from them, you can do the same as well. Some people even arrange a match up online before actually picking it up, once met he will pay with his credit card (for mileage bonus), then you pay him the price + margin in cash. The benefit of doing it in and out of Apple Store is some degree of guarantee and safety, that you are getting a real unit, and the exchange is inside a well guarded public mall.