$729 - Flights to Melbourne Australia from San Francisco on Air New Zealand
Flights are in September, October, and November. May need to fly Monday-Wednesday.
Flights typically have a two hour layover in Auckland, New Zealand, which is more or less on the way, so not too much of a detour.
For alternative flights to Australia, I usually check the Qantas site. Their flight information is supposed to be pulled in by all the major flight search engines, but I like to double check just in case because sometimes there’s a lag between when they announce a deal and when the third party sites find out about it.
Flights on all major airlines to Australia are starting to go up in price, so if you’re thinking about going this Fall or Winter, I’d suggest buying a ticket now.