Speaking as an Aussie, if you were going for iconic stuff there are a few options for inspiration:
For one, directly koala-related, there's Blinky Bill and his friend Nutsy.


Other iconic Aussie stuff that isn't as often used for things includes:
Surf lifesavers,
especially the
Bondi Beach
ones, in their red and yellow - they have their own TV show and everything.
More common stuff includes the standard ones like Ned Kelly in his improvised armour and so on.
I hope that helps even a little - I'd be glad to help some more.
