Where is the best place to get the Tamiya spray paints?
Sherriffs in Paramatta has the best price I've found, under $10 a can.
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.