I think comparing prices between countries is quite fair.
I guess it's a start...
But with limited understanding of the true costs, you can only guess at the real economics involved.
Bare in mind, many, many manufacturers use the massive global markets to achieve market share and cheap purchase prices for their components etc. They use back-waters like NZ as a place to make an actual profit.
There's no way on this earth that NZ's economy can compete with the big players and deliver super low profits through local retailers (physical and cyber) but that's why everyone's free to shop on a global basis now.
It's getting off topic, but for the OP, they're lucky enough to be making calendars that have NZ's calendar on it, so they won't be subject to as much parallel importing pressure as some other products in the marketplace.