A few years back I rented a TB20 from Basair at Bankstown and went up the east coast as far as Townsville.
A great trip but if you are thinking of going that far then you need to adress the issue of staying alive and being found if you have a forced landing, untill you have flown in Australia you won't understand just how big the place is and how few people live away from the coastal strip.
www.basair.com/rates.shtml