Funny, a few weeks ago a buddy of mine had the same idea.
I don't know about the legal situation in Oz, but over here that would be practically impossible because the federal states own the rights to the frequencies and the obstacles for renting frequencies make it virtually impossible to broadcast as a private person, no matter at what scale.
The legal situation is so tight over here, even those little FM-transmitters you can us at home or in your car weren't allowed until recently. And even now they have to be so weak that you wouldn't get the signal from another car if you would stand next to it in a traffic jam.
I'd be quite interested about the situation in Oz, the US... well basically anywhere besides here.
If you'd want to venture into terrestrial broadcasting as a hobbyist over here, you're only chances are either university radios or other non-commercial "public domain" stations where basically everyone is allowed to participate.
I gathered first experiences at a university radio too, then interned at a big commercial station and am now a weekend host over there.
So if you'd be German I'd tell you to forget about it an either go to a public station or go down the internet radio route...