Hi Dennis,
I went to HK last year and tried to find a model train shop. Eventially I found Lee Kwon in Kowloon, it is in the market area not far from the main post office.
It is a small shop but packed to the ceiling with boxes. It has a wide variety of things all imported which puts up the price. It is a pity really that as Hornby trains are manufactured in the area there might be some kind of bargain outlet here. However, it seems as though they are imported from UK. Lots of German, and some UK and US stock (considering the physical size of the shop) and the shopkeepers (husband and wife) were quite helpful. I did get some track at discount prices but it was Atlas N scale and although ok doesn't compare in quality with the Fleischmann I already have. I bought an N scale Fleischmann loco which is a real gem, but I can't find it listed anywhere on the internet to compare a price.
There is a factory in HK too but I couldn't get a phone number to see if they had a retail outlet... you might have better luck with that one.
Hope this helps,
Brian