I have some experience shipping to Australia. My little internet based sideline business (in addition to a full time job, playing in two bands, and uh oh yeah... a marriage) is involved with tournament water skiing, slalom course skiing. I build and sell portable and permanent slalom course setups and Australia is a pretty good market for our brand, I ship several courses a year there.
For just an off the top of my head guestimate, to ship say an Epi T-Bird in case and properly boxed and padded, you're probably talking $350 USD-ish FedEx to the customer's door. My guess is no one would mess with it for less than $100-ish for time and labor so you've got that plus the cost of purchasing the instrument. Say you give $250 - 300 for a Bird (preferably) with a case, you'd be looking at $700 - 750 USD (920 - 986 AUD). And that doesn't include any import duties, taxes etc. Not too sure you're saving anything.
I once tried to figure out a way to get a guitar to an Australian friend for less than what it cost in Oz... Sadly, ya just can't do it.
It's sad because my friend was a disabled Vietnam vet on a fixed income and the Epiphone Casino that he wanted ($500 USD at the time) cost over a THOUSAND dollars AUD. I was going to find him a good used one to save him as much money as possible, but after shipping, duties, tax, insurance, etc it's not much cheaper.
His family ended up pitching in together to get him a brand new Casino for Christmas, so the story has a happy ending, but man... The way guitar distributors operate in Australia is freakin criminal. I still get pissed off when I think about it.