There is a little shop in the ground floor of the Sham Shui Po computer market. As you come out of the MTR turn left and walk one block while keeping the computer mall on your right - till you see MC Donalds on you left. Turn right and cross the street. Walk about half a block and enter the computer mall at that point - on the ground level next to the escalator that leads up into the mall is a small ( only a counter basically ) watch shop. The lady there will sell you anything you want - she can order - for about 30 - 40 % below retail.