Road or plane ?. Australia is more beautiful at ground level but cheaper flying.
The Tiger company is owned by Singapore Airlines and is the closest thing to Ryanair I found there. With it we flew from Melbourne to Perth - 2,730 km away - for 1 Australian dollar. The return ticket was somewhat more expensive - about 120 AUD - but it was equally profitable and saved us a lot of time.
Many people advised us not to use this airline because they said they could cancel flights without prior notice and other stories of bureaucratic problems but the truth is that we had no complaints and the flights were punctual and without major problems. Of course, cheap tickets are the most untimely hours.
That said, the authentic Australian Ryanair, including the subject suitcases and so on.
The second one we tried was Jetstar, a subsidiary of Qantas - the main Australian airline - and Spanish equivalent to Vueling.
The prices seemed somewhat higher than those of Tiger although we paid about 130 AUD for the journey between Cairns and Sydney, in which we covered a distance of almost 2,000 km. So it wasn't too bad either. In addition the schedules are somewhat better than those of the tigers of Singapore.
The Virgin Airlines subsidiary, Virgin blue, is the third option but we never found better deals than the other two.
However, if you have enough time and money to travel the endless, lonely and wild Australian roads, I recommend you do it because your contact with the wild nature will be almost unequaled. We did a couple of Road trips between Sydney and Melbourne and along the West Coast and they were the best of our whole trip around the World.