I'm sure it's do-able.. But when you have freighting there&back, quarantine inspection, carnet and insurance on your to-do list, then I'd seriously consider renting a bike, which would get you rid of all those.
But the best option will of course depend on your plans, how long you would stay in Oz, and how long is the trip you want to do. There is no one definite answer, you´ll need to decide, and it´ll naturally depend also on the deal the rentals offer you.... But renting is usually better for shorter trips/distances (and typically inside 1 country, but in Australia of course you won´t have the problem of crossing borders), while bringing your own might be feasible, if you´re staying for a longer period of time.
I went to the US for 6 weeks, and ended up renting a bike from there. Any longer, and I´d probably have sent my own bike by sea, or bought one from there (oh yeah, that is one more option to consider!)
Last edited by pecha72; 25 Jun 2012 at 09:56.