The boxset is basically like the "collector's edition" of the volume 1 DVD. the box that comes with it is supposed to contain all the DVDs when you buy them...damn, it's an expensive exercise, but it's Australia, what do you expect?
I think the standard is a bit cheaper than that. That's the 20% Cooler edition, it has Part 1, a collectors box and an "exclusive gift". I think the normal is about $15 AusD.