Tokyo Mart
27 Northbridge Plaza, Northbridge.

Fashion Land
Northbridge Plaza Northbridge

Maxim's Video
Corner Thomas and Quay Streets, Haymarket

Po Hong Books and Stationery
410 Sussex Street, Haymarket.
Pretty much the same as the Po Hong store in Melbourne.

A Zone
This is in Market City. Go up the escalators which are opposite a small travel agent thingy. You should see a toy store, keep walking straight and the shop should be on your right. It has posters, calanders, models, toys, CDs and more.

Modeller's World
Run by the A Zone people. It is in the arcade on the corner of Lt. Hay street and Dixon street in Chinatown.
Cartoon Zone
In Sydney on the top level of the QVB (Queen Victoria Building) there is a shop named Cartoon Gallery. Their URL is www.cartoongallery.com.au Their webpage showcases their merchandise and other various information regarding their business.
Information provided by Zero Nexus