Yeah, this is a tough one!! I've sent a lot of bikes from the states/japan/korea to aus and havent found anything cheap. We have tight restrictions on the size of parcels that our post will take. I've broken road bikes into three boxes in usps and gotten it here for about $200US at the cheapest, but now thats apparently a no go. I've just ordered another via DHL, I think and its about $300 in one box but very fast.
I used a courier company from Korea called CJS, i think and they were really cheap! I think it was on a ship. Maybe $150.
Sorry to be the bearer of bad news... but i did a fairly long search for companies when leaving the states, and nobody was into it. Either they were companies that specialized in huge volumes and a bike was too small to take advantage of it, or they dont want anything as big as a bike.... it killed me!
Something that you may want to check out is the companies that now transport your bike to your triathlon, wherever you are racing. I think if you got onto them, they might be into it. Whereabouts in Australia is it going?