Welcome to the forum

I am not sure what your question is.
- Paying cash?
- Or hoping for an award?
- Want to get miles into an airline freq flyer program?
- Looking for the cheapest fare?

Via Asia to Perth may be the best way

Airline information
Airlines that fly in Australia domestically
- Virgin Australia (Delta partner)
- Jetstar (a low cost, low quality carrier owned by QF)
- Qantas [OneWorld]
- Tiger Airways (a low cost, low quality carrier with low fares part owned by Virgin Australia)
- Regional Express Airways (REX) Regional airline

Airlines that fly USA/Canada to Australia (most from LAX) are
- United [Star Alliance]
- Qantas [OneWorld Alliance] (AS partner)
- Delta [Skyteam Alliance] (VA & AS partner)
- Virgin Australia (DL partner)
- Hawaiian, via Hawaii (AA DL & VA partner)
- Air NZ, via AKL [Star Alliance]
- Fiji Airways, via Fiji (AA & AS partner)
- Air Tahiti Nui (last segments on codeshares) (AA & DL partner)
- Air Canada [Star Alliance]
And others via Asia & Middle East