I don't know any, either. I live in New Jersey, not Australia.
Make friends with someone from Australia and ask them to help you out, or keep trying Google. You'll have to search for a dealer that sells second-hand electronics. Or better yet, start trying Japanese electronic stores, where you may have much better luck (remember, the Gigabeat X was also sold in Japan).
Anyway, this is going to be my last post on this subject matter, before it starts to veer off topic. I can only confirm that it's going to be quite difficult to get a Gigabeat X, and this is based on personal experience. All I can tell you is that if it comes down to the fact that you can't get one at all, just get an F, or get a Gigabeat S and wait for the port to arrive.