Yes almost every paint supply place can do rattle cans these days, particularly places that specialise in automotive finishing.Not especially cheap mind you.
A 400g can is plenty for the colour coats. If you happen to find a Dulpicolour in the smaller 125g cans, it is enough, but I always seem to end up buying a second one to tidy up boo-boos.
Just did a quick google and here is a place in Melbourne that does it. Looks like they'll even ship it so you might not need to wait for lockdown to lift. I'd contact them with what you are after and see what they say.
https://autopaints.com.au/index.php?...t&product_id=6