Found out from a friend
http://www.cic.gc.ca/ENGLISH/VISIT/ETA-START.ASP
If you live in a visa waiver country (NZ is) then you do the eta online and pay $7CAD so not as much as the US ESTA.
Leniency period until 9 November after which you have to have the authorisation.
Luckily the friend told me as I am off to Canada soon but then will be departing on 5 Nov so should fall into the leniency period.