Here's a list of things I found:

New Zealand grown potatoes and onions are not only cheap per kilo than in New Zealand, but they are also three times the size of what New Zealand supermarkets sell.

Petrol is $2.41 NZD per litre whereas New Zealand it is currently sitting around $3.35 NZD per litre.

This is an island nation that is smaller than New Zealand and stuff has to travel further than here in New Zealand and yet pound for pound it's cheaper.