Currently there are excellent fares between the US and Australia.

Flights operated by Virgin Australia between Los Angelos and Sydney seem to do the trick here. Connection flights are mainly operated by Virgin America and Delta.

Direct flights start at US$ 426: LAX-SYD

From San Francisco prices are around US$ 422: SFO-SYD

Even from New York prices dropped to US$ 577: NYC-SYD

There are a lot of similar routings within the US. Just try the airport of your choice. I saw available tickets at least until the end of november.