Interesting question you posed there Steve and it opens up possibilities that I had not considered before, viz.
Land in Australia falls into a few different categories, ie.
. Private land - might find some farmers who would OK a camp
. Aboriginal Lands - definitely permits required to camp & even transit some, no grog permitted and more popular areas like Uluru are leased back to the government to be managed by National Parks - camping permits/fees etc.

Then you have Crown Lands, either Local Government (Councils), National Parks, though they are managed on a state by state basis, and then State Forests.
Some councils have designated camping areas on beaches, lakes, rivers etc., and permit/fees apply as they do for all national parks where camping is allowed.

The interesting part is that not much thought is given by too many I suspect to camping in State Forests, and saving last until best, it is absolutely free insome states at least - Recreation: Escape into adventure in State forests of NSW! for NSW for starters and also in Victoria as well but Queensland lump theirs in with National Parks and a small fee $4.50/d is payable - https://www.epa.qld.gov.au/parks/iaparks/gds/

In that instance, you might as well go for a national park which will have somewhat better facilities, and that will be true also for NSW and Vic.
Some NP and other camping area links:
. Environmental Protection Agency
. Ku-ring-gai Chase National Park - Camping & accommodation
. Myall Lakes - New South Wales - Australia - Travel - smh.com.au
. Parks Victoria: Great South West Walk page
. 60 Great Short Walks*
. Discover Moreton Island - Queensland, Australia
. Welcome to North Stradbroke Island
And this site gives an idea of costs of some organised trips which you can use as a reference: Adventure Programs - UQ SPORT, The University of Queensland
And for general info: . 4WDing, Camping & Caravanning around Australia @ ExplorOz

For other states, or for any of them at any time, just google up the state, followed by "national parks" or "state forests" and with LGs just the name followed by "camping", for instance, "Noosa northshore camping"
I was camping one time on the Snowy River and we must have been outside of the Snowy Mountains NP, for it was free and an idyliic location amongst boulders and sandy shores.

When you're in Australia, you'll find that Libraries will often have great reference books apart from free internet, and then if you find out where the National Parks ofice is in any city/town, they will always have free detailed brochures on individual national parks showing trails, facilities and costs.
Bookings in many coastal NPs can be difficult to get over Xmas and Easter holiday periods.