For those who thinking to have budget vacation in Hong Kong, you can logon to this Dragon Hostel and check out their price for different types of room.
It isn't a HOTEL style, but it is good and clean enough for you to stay overnight there. It is something like HOSTEL and it is located in the most busiest area, Mongkok. And just opposite to "Lui Yan Kai" (The lady's street, 女人街).
I stayed in Dragon Hostel before, it's good as i just paid HKD480 for 5 beds in a room and even with toilet attached. And, the HOSTEL just nearby to KCR and MRT station.
But, it's quite difficult to book the HOSTEL since a lot of foreigners like to stay over there. Anyway, you can try your luck by dropping by to their website.