With Heart of the Swarm coming out soon I haven't done my research, but wonder if anyone else here has:
Does the HotS region need to match your WoL region?
What effect does HotS regioning have? What other regions are shared with AU these days?
What price have people found this for?
I've done some research now and this is what I've found (please correct if any of this is wrong):
1: All region locking is removed with HotS, so you can buy from any region and play in any other region.
2: This is still unknown. The answer from 1 implies that it doesn't matter, but there is no clear answer.
3: As far as I can tell CD Keys are only legitimately sold from Blizzard, who charge too much for it. Boxed versions can be had for $40 + delivery, which almost always goes past $44 which is the typical local cost (BigW/JB). So it seems $44 is the answer without trying your luck on somewhere that will email you a key. Local copies also removes the risk from question 2.