There's usually something for around £650 at that time of year... It's worth clicking the 'sign up for special offers' button near the top right corner of the
www.airnz.co.uk website. Right now the best offer I can see is £761 - details here:
http://203.167.234.188/uk/airfarespecial/1660.htm
Edited to add: oops, I see that £761 is not until April next year; northern autumn fares are £895. There should definitely be a better deal than that released in the next month or so, unless they are trying to get a premium as a result of the long haul cabin refit?