There are free, open source alternatives, you know? But if you must use Windows (because of a specific business app or because you are a keen gamer) then that's the price.
While you are correct, Microsoft sells the same upgrades overseas at one third of the NZ price (eg if you need 3 licences, then the US Family Pack Upgrade is NZ$200 for 3 PCs).
That is my major complaint. Why not here too?
If Microsoft can afford to sell Family Pack upgrades in UK, Canada, several EU counrties, and sell upgrades to students for $US30 with problems, and give away upgrades to testers, launch party hosts and lucky twitterers, that all indicates that NZ$600+ is too much to pay for 3 upgrade licences in NZ.