Just saw this in the Harvey Norman catalogue. World of Warcraft - Cataclysm expansion for $38 (pre-order). Seems to be cheaper than any price I've seen so far.
Update: I've noticed a number of people have had to point out the online catalog to get the price of $38. It is actually on the printed catalog, so just pick one up from the stand at the entrance and show it to them.
Sweet, I wanted a box to go with the rest of mine, $2 cheaper than the digital option (unless the AUD keeps going up).