Apparently there is a sale starting on 13th June with Singapore Airlines, with prices starting at £359 return *including taxes* to Christchurch...!
Flights need to be taken between 01 sept-09 December 2009 or 16th Jan - 31 March 2010. For more details, see this page:
http://www.hotukdeals.com/item/42087...-oz-and-new-z/
Hope this helps someone...
Cheers!
Pete.