Travelling at the moment and came across this eSIM provider that appears to offer cheap prepaid 4G data in NZ.
$9 USD for 3GB of 4G data (through Vodafone's network) with 30-day expiry.
As it's eSIM only it does require a compatible handset (eg iPhone XS, XR, 11).
For comparison, 2gb of 4G data on Spark prepaid currently costs $29.
Thanks for sharing. I recommend trying this for finding a good SIM card for your travels:
https://esimdb.com/