Welcome to one of the most under competed and over priced routes in the world. QF holds almost 80% of the market share on direct flights between the US and Australia, the rest is held by UA.

Your only other choice is to stop along the way from the US, or to take the AC flight from Vancouver to Sydney, which is probably a good option, but still not cheap. Getting from North America to Australia is just not cheap.

I would have a look at the Circle Pacific fares. In money terms you probably won't end up spending any less, but you'll get more bang for you buck by being able to have a stopover in NZ and somewhere in Asia as well as your trip to Sydney and you can rack up the miles so you can get this trip for free next time.