As for OF, try
Anytime Concept shop u can also find it in "Juice" in Causeway Bay. i think they're the official stockist. the address is in the shopping guide thread. Other than that, some reseller shops around areas like Mongkok, Tsim Sha Tsui, and Causeway Bay stock OF gears.
For supreme, try
Suburb and basically reseller stores as well
hope this helps