There's a few shops in Sydney that will mix the paint colour of your car or what you need and put it in a spray can and average around $25 dolalrs each.
There's one in Carramar near RedRooster (forgot what road it's off), it's off the hume, coming from Bankstown, it's the road before Sizzler's from what I remember.
Where are you located?
It's easier if you give them your petrol lid thingy (I'm totally blanked at this time) in my experience, on my previous car I gave them my colour code and it was a Mazda 626 Emerald Silver, turned out to be 95% silver and 5% green. On my new car it's very very very similiar.