There's no cheaper way of getting around, particularly if the place you are attempting to get around is a capital city. If you aim towards commencing your city and suburban journeys between 9am and 4.30pm, you'll find public transport easy to use, relatively stress free and unbeatable in terms of value for money.
City by City guide to what you can see by public transport in Australia's capital cities
Vehicle purchase, a cheap alternative for the overseas visitor
Purchasing an older vehicle is a viable option to renting one, thanks to websites like Cars 4 Backbackers and Travellers Auto Barn which provide a useful service for travellers wishing to take up this travel option. Travellers can purchase a cheap car, campervan, station wagon or 4wd through the website, and when they have finished with it when they are ready to leave Australia, they simply sell it back or advertise it on the website and sell it to another traveller seeking their own set of wheels during their visit to Australia.
Vehicle transfer, the cheapest way to rent a vehicle
Online motor vehicle relocation services provide really cheap rental cars, motorhome and campervan hire. Amazing but true, some cost only a dollar a day, though most times they are free.