One way to check if what you're finding is a reasonable price, is to search in Google Flights, where they tell us that $1585 (presumably what you found when you said "$1600") is $1193 cheaper than "usual", and that it "usually" would cost between $1650 - $3900 CAD.
However you can see that if you booked it 49 days ago it would have been around $1400 CAD. So if you keep tracking the price, maybe it will go back down to where it was 49 days ago, but also it might go up to where it "usually" is which they say is $1650-3900 CAD.
However the last time I traveled between New Zealand and Canada it was much cheaper, probably because I flew from New Zealand to Vancouver first (with a beautiful stopover in Fiji!), then got a $30 flight from Abbotsford to Hamilton with Swoop airlines. I used Pop-a-Ride to get from Vancouver to Abbotsford for about $10-$15 and Hamilton to Toronto only costs about $20 on the GO train and a few bucks to get from Hamilton airport to the GO station by bus.
As pointed out in this comment, you might want to consider staying with a friend overnight in Vancouver if possible, to give some buffer time before the final flight to Toronto, just in case there's delays.