Qantas has low ticket prices at $574 round trip from San Francisco to Queenstown, New Zealand ZQN for travel in Sep and Nov 2018, then late Jan-March 2019. Ticket prices to Auckland, Christchurch and Wellington are about $670.
Momondo searches pull up fares about $50 lower for some itineraries.
The catch is these low fares only trigger at minimum 14 days between outbound and inbound flights, so you need to have at least two weeks to travel. October prices are about $100 more and flights are priced much higher from mid-Dec to mid-Jan.
Qantas San Francisco SFO – Sydney SYD – Queenstown ZQN – SYD – SFO
FlightHub.com online travel agency ticket found in Momondo.com search
$513.77 round trip SFO-ZQN Nov5-19