Sherriffs in Paramatta has the best price I've found, under $10 a can.Where is the best place to get the Tamiya spray paints?
Hobbyco, and other hobby stores in the city.
Online if you get a whole lot. I like Rainbow 10 for the Gunze range.
http://www.rainbowten.co.jp/english/
Even HLJ has spray paint, but no bottles.