Despite what our friend above has to say let me tell how it is as a resident here in Australia.
It really depends on where your friend wants to travel. If she is going to be in Perth then she will find that there is a good public transport system in place with plenty of buses and suburban trains.
If she wants to travel outside of Perth to major regional centres in Western Australia then, once again, there are trains and buses to most major centres.
The cost of public transport is relative I guess. Most Australians would think that it was quite reasonable in the circumstances.
Travelling between capital cities is also relatively easy and there are plenty of discount airfares even though there are not as many airlines in Australia as there are in the US.
If your friend needs a car then it will probably be cheaper in the long run to spot hire a car when the need arises. Car rentals within capital cities are cheap but if you want to travel outside of the capitals then rental can become a bit expensive.
If your friend needs anymore help perhaps they can hit me up via the contact details you will find at the end of the link in my sig.
I'm sure your friend will love this country but tell them to pack some warm clothes - Western Australia in winter can be a bit on the cool side
