Good luck on this. There are an awful lot of things that you can't find in Australia for various reasons.
One thing to try is buying online from a U.S. site that ships internationally (a few do, because they're big enough to have Dangerous Goods contracts with the big carriers).
Both of those definitely ship to Australia. Whether or not they'll have what you're looking for... well, that's another matter. I find it quite difficult to find pure parfum no matter where I look for it.