I actually prefer HMV Australia - unlike some of the other Aussie e-tailers, their shipping charges tend to be really low for sets. And the thing I can't figure out is their web site is easier to use and their customer service is better than the parent company in the UK ... and the UK HMV charges through the nose for shipping. Go figure.
http://www.hmv.com.au/
I've also used EzyDVD and Atlantic - both excellent as well.