Wo Hing Hong at the junction of Leighton Road and Matheson Street ( I think) in Causeway Bay. They have a lot of other frozen stuff there at very reasonable price but the quality may be be 1st grade. Happy hunting!
Peggie has the right of it: Woo Hing Hong is the place for grain-fed Canadian ribeye, NZ tenderloin, Australian lamb (about 80-90$ for a rack). Get ready to line up and know what you want to buy. Long on quality but short on service here.