MONG KOK
In's point:
Nathan Road around 530
Yau Ma Tei station D exit. It should be the first place you need to go and then walk forward to the direction of Mong Kok you will see every store below. There is a map on wall in every station. Check it out before you quit.
Cino Centre:
Nathan Road 592-582
A few toys shop inside.
CTMA centre:
Sai Yueng Choi street south 1N,
A hottoys shop inside. This street parallel to the location of Cino Centre so I usually walk in this street and skip Cino.
Richmond:
Argyle street around 107-111,
Two entry for up and down. Don't miss the downstairs entry on right.
SHAM SHUI PO
Two station from Mong Kok, Fuk Wing street, near Sham Shui Po station D2 exit. Most of the shop selling bootlegs, still a few legit shop.
WAI CHAI
Tai Yuen Street, Wai Chai station A3 exit, only a few toy shop locate in it.
Nicolas Cage just stop by.
There is a big store selling old toys near the mall of Tai Koo, which is close to me.

Most of the toy shop open around 3pm. Don't go too early.
You're welcome to ask me out if you need a guide.