If you are into a budget hostel, you cn try Auguster's Lodge...

They only have 3 rooms for rent and I'd booked 5 person room for HKD300. However, the room is very small and using common bathroom.

If using small bedroom and sharing common bathroom is not a prolem for you, then you can give this a try although it might look old from outside of the building.

Walking distance to tourist attraction an Lisboa casino.