I don't know of anywhere in Australia which sells the individual Mr Color paints. You may find the occasional hobby shop which sells the small three jar sets and Mr Metal Color, but not the general line.
As you may be aware, the Mr Hobby Aqueous Hobby Color (aqueous acrylic) line has been widely available for some years, but following the discontinuation of the high-numbered paints in this line, I'm unsure about these too (my LHS stopped carrying the aqueous line).