My friends and I went to the Harbour City Bazaar 2 weeks ago and bought many winter clothes. Many good quality kids jackets are below $100. The material is warm enough for winter in Hong Kong.
I also know a shop in CWB which has export-brand jackets for about $90-120. You can PM me if interested, and I'll send you the address.
Many BK moms & dads mention about bazaars and baby fairs from time to time. You should watch out whenever there are posts like these.