Shipping from the US to Australia is a killer, I have sent 3 model Ms (2 M101s, and 1 M122) and the shipping has been between $40usd to $50usd which will make any good deal you find here into a not-so-good-deal.
Best thing to do is put up a wanted ad on your local version of online classifieds, and then look up Electronics recyclers within driving distance and ask them if they have old ibm keyboards and if you can come look.
Watch for local electronics junk days, go to garage sales, check flea-markets, check second-hand stores.
Look for ads from computer repair places and call them and ask them if they have any in back rooms.....
Persistance pays off. There are lots of them around, you just have to keep knocking on the right doors.