There actually a few ways to save money. Some or not that legal (so illegal?), well anyway here is a list about how you can save some money.

free refills at McDonalds
If you buy a coffee you can get free refills (at the McDonalds anyway...). Now, don't throw your cup away but keep it with you. Next time you see a McDonalds you go in and refill your cup. But do not try the drive in, they probably won't be very happy if you try it over there... This can save you $100, 00 at least...

buy yourself a car
If you get yourself a car you suddenly have a lot of adventages you probably don't even recognize yourself at the start:
-sleep in a tent just along the road, so you won't have to pay your stay for the night
-cook for yourself with (with all the pans and pots you have), a lot cheaper
-save on coaches and you're more flexible as well
-get your car full with people so you can share the petrol

spend Australian dollars if the exchange currency is high
If you have some money on your account back home and the exchange currency is high, than it's better to spend Australian dollars. You better save your 'money back home' for other times when the exchange currency is lower. You must have Australian dollars though...

'illegal' camping
Sometimes you arrive at a campsite at night and you can not find the receptions easily or they're is no one there. Just put up your tent, get yourself a relaxing and refreshing shower and leave early the next morning...

save money on petrol
If you're planning to go to the Outback, you better buy yourself petrol before you get there. Fill your car up and fill all your jerrycans. The petrol in the Outback is alot more expensive than outside there...

VIP card
Get yourself a VIP card and you will have lots of discount on things, like paying less for a night in a hostel, develop your phot's, ...

Don't panic, there are a lot more suggestions to come. Any suggestions yourself? You know where to send me a message...