Greg:
Where I live, it costs ten bucks for the 'Permit to Purchase', and only 5 bucks for the registration.
Other southern states are probably more expensive.
Antique licences and rego are both free in the Northern Territory.
Regarding the reduction in gun crime in Aussie since the new restrictions, there was a well-circulated report by those with a 'vested interest' to say that the buy-backs were very successful at reducing fire-arm deaths in Australia, but a recent scientific paper has identified the flaws and deliberate deception in that report. I don't have the details to hand, but will post the references when I am back home.