Air New Zealand has some very aggressive sales right now from the US West Coast to Australia for under $500 Round Trip. These fares usually stand at $800-$1,200 Round Trip.
It comes up on Google Flights and Expedia but Momondo has by far the best prices. Here is the Round Trip between San Francisco and Gold Coast for $507.
Fares come up from February until June 2018 and are available from Los Angeles and San Francisco.
These destinations seem to work:
We suggest to book now and take advantage of the 24 hour free cancellation that most sites offer if needed. I never had an issue cancelling a ticket without penalty on Orbitz, Expedia or Priceline (though they are about $100 more expensive for this deal).