Hi Willow!
Central Book Services has promised an Aussie ebookstore up soon -
http://www.ecoreader.com.au/get_ebooks.asp
In the meantime, your best hassle-free bets are the DRM-free stores, which don't tend to have geographic restrictions. Of course, they don't usually stock the bestsellers either :/ Check out
Smashwords and
Feedbooks for some good indie fiction
Disclaimer: I have work on both, and I'm biased!