Well, I just made a post in the good deals thread...might be worth looking at
You could probably manage the trip for under $1100 to NZ...not sure what the fare rules are, but you could also stop over in MEL potentially for a bit more...that flight is from LAX, but I do think you can find a flight to LAX on those dates for under 300$.
$1100 or lots of hard work and stress and lack of flexibility with dates with 75k miles....