I had very specific parameters for my saved searches, but these seem to have been over-ridden by eBay, who apparently know more than I do about what I'm looking for....

It most certainly WAS possible to save a search with Aust-only listings -- in fact, my email notifications still say 'New items that match: xxxx, Located In: Australia' which is how I set them.

When I'm interested in looking at items located overseas, I will choose to look at items located overseas.