For anyone looking to order in Australia, this is the cheapest source I've found and currently has a 19% sale on the book.
Very odd. Both Angus & Robertson Bookworld and Booktopia claim that the RRP is $73.65 AUD, but it should actually be $66.95 AUD. They are both charging less than that. But, I wonder why they are overstating the RRP.
Well, how about that? I received an answer to my enquiry in the middle of the night. Apparently the Australian version of RRP includes 10% GST. So, that works out to exactly $73.65.
That would explain it. It's nice to be able to pick it up on a small sale however - I'm really looking forward to reading it.