$25 per month for 12 months, usually $50.

Free SIM Card included or e-sim
UNLIMITED Data at a max speed of 50Mbps for a month*
UNLIMITED standard calls/TXTs to New Zealand & Australia for a month^
All for use within New Zealand

https://www.mightymobile.co.nz/

Cheapies thread
https://www.cheapies.nz/node/49926