Good luck! There are so many Australian natives that I wanted to try. But that's much harder now that I've moved to the cold confines of zone 7.
I still have one plucky Bailey acacia, which is actually hardy down to 20F. I keep dreaming of a bonsai with that surreal blue feathered foliage.
What's funny is that if you search for "bailey acacia bonsai", one of the top hits is actually my own bonsainut post where I'd listed a few for sale when I moved away from California. Not a great sign!
The other one, which I don't have, is the stately Geijera parviflora. But sadly, online scammers have completely obliterated it's name beyond all recognition such that 'Australian willow' now refers almost exclusively to online scammer sites selling garbage Salix cuttings.