Can't believe noone has said it yet, but, if you think NZ is expensive then don't bother coming near Australia.
Having lived a fair mix of each in the last few years in each, I can tell you the following:
Groceries: 20% cheaper in NZ. (Oz supermarkets are taking the piss in my opinion!)
Beer: 30-50% cheaper in NZ.
Real estate: 30-50% cheaper in NZ.
Telecommunications: on par.
Can anyone tell me what exactly is more expensive in nz compared to oz? Can't think of anything myself.
Btw. Beer. In oz a 24 pack of coopers is around $43. $19 something goes to the brewers and the rest to our taxman. That is why even after shipping the kiwis can buy it for less in a supermarket!
Lifestyle and all in mind, yes, I'd do exactly what I do now for 30% less in nz because it would buy me the same if not better a living.