The B3 Inn is maybe one of the best budget-options in the city. Wilson (the owner) is always reachable and happy to answer questions, give recommendations or help out if you have a problem (he went to the laundry with me because it was hard to find and he wanted to make sure I pay the "real" price and not a tourist-price).
The room is a typical Hong Kong room - size-wise. But compared to most other options, Wilson is all about keeping the place as clean and cozy as it is. You enter the small place and you get the feeling the place was built just yesterday.

I felt very comfortable, the bed was very cozy and it was even very calm and relaxed even though the place is just 1 min away from TST.

If you're thinking about going to HK and this place is still available: Book it before it's fully booked. As far as I understood Wilson, there are only 8 rooms.