score:4
You may want to play with your dates. Beginning of April will put you into Easter travel time, but for example April 18 to October 2nd would make the ticket through Brisbane and LAX in the range of about US$1800, which at the current exchange rate would be about NZD$2070. On Kayak.
EDIT
One more thing. Consider buying AKL -> LAX and LAX -> YVR separately.