I live on the Sunshine Coast, about 100km north of Brisbane.
As to prices and availability, the RHD 500s are becoming rare as most have probably been consumed by tin-worm by now. The ones that are left seem to be coveted by their owners and exchange hands for reasonable amounts of money. For example, there is a nice fully restored blue 500F, coincidentally also for sale in Brisbane, for around $AUD20,000 (approx 12000 euros), a Giardiniera for sale in Sydney for $AUD30,000 (~ 18000 euros) and a '695 Abarth' for sale in Melbourne for $AUD22,000 (~ 13000 euros). The last one is just a tricked-up 500F and not a true Abarth. There is a very active South Australian 500 register that I may join, if they'll have me .....
I've been looking for some time and literally stumbled on it a little while ago. I got it at a good price because the owner was very keen to sell and the car does need a lot of work. I imagine it will be a labour of love over the next couple of years.
Incidentally, you also don't see many Niki 650s or Fiat 126s in Australia. I'm not sure why.
I'll post some photos on the Garage section of the bulletin board.
Regards,
Chris