As far as I know, none of shoes can be found in HK (the place where I live). If you want to buy new model Yonex shoes, I do know one place - Taiwan. I have recently bought a pair of SHB-92 (similar to SHB-90, but with different style) in Taiwan.
In fact, you can find badminton more badminton equipments in Taiwan, e.g. you can find new models for Yonex, Carlton and Gossen there (but I only know one and two shops in Taipei to sell these equipments).