Hong Kong is an expensive enclave - in the tourist areas, which is most of Tsim Sha Tsui and the northern parts of HK Island, the shops cater to high-end customers with designer products. Plus as others have said, Western sizes are hard to find. I would not bet on finding appropriate shoes easily, at least not in TST or in the tourist areas. I would encourage you to look for your shoes at home first and buy them there, because you could miss out altogether if you really wanted to wait for HK/China. Then if you can find a shoe shop in Hong Kong and do find some shoes you want to buy, you can celebrate. I will give you a few tips though: if you want to stay in an area that is less touristy and more an authentic old neighbourhood, we stayed in Sai Ying Pun some years ago, specifically at the Citadines. There is a water view and ferries, tram and MTR close by, as well as a wet market and a shopping street (forget your shoes here, not that kind of neighbourhood). And if you want to shop where the locals do, be prepared to go out into the backblocks. They have theme streets (toy street, pet street, etc). Once we went on the metro to the end of the line on HK Island out to Chai Wan, where there is a shopping centre. No tourists, also no haggling, as it's just a place for locals, so maybe you could look for your shoes there (no promises, though, so don't depend on it). Once on a metro we went north and came across an ice carving festival. Another time we caught a bus to the end of the line and found a suburb with a department store (again, all locals). I also recommend Lantau Island, where there is a Disneyland (spend less time there) and a cable car ride to a big Buddha statue, and then a bus ride out to the fishing village of Tai O, where you should have a seafood lunch and a ride on a boat around the village. There are wild cows there and if you are lucky they will come up to you. We have been to HK quite a few times but not for some years now, but I think my advice still stands. Get out, don't spend much time in TST, the MTR is easy to use and can take you to some fantastic areas which have no tourists (and no English, but that is part of the fun).
Lavandula