Had to pickup some touch up paint myself today.
First I tried Autobarn, they would have matched the paint code, but had run out of white (colour i needed)
As I live on the Northern Beaches they recommended Autolac in Brookvale (Winbourne Rd)
Stopped by there this arvo and picked up a 250ml pot of QM1 - White for $30.
If you are in the area I'd suggest giving them a try.
But I am sure there are other Auto paint shops in NSW, just giving my input, hope it helps.