In Hong Kong you need to go to the backstreets of Mong Kok and Jordan. There's a whole 'sports street' back there selling sneaks and equipment. Stuff is genuine (certainly rackets will definitely be). Prices are cheap. The street you want, if I remember correctly, are Fa Yuen St and Sai Yee St.
Go here (
http://www.centamap.com/cent/index.htm) and enter 旺角 on the search box on the left and click on one of the MTR links. You should be able to see Fa Yuen St on the right of the map.
There's also a good tennis shop in Causeway Bay, but it's hard to describe its location. It's under one of the circular walkways that go over the street.
Good luck. Remember, bargain like a *****.