Not sure when this expires, but China Southern are doing sub-$500 flights from Melbourne to China. There seems to be a lot of dates in March and April. Posted a few examples below.
Shanghai:
https://www.skyscanner.com.au/transport/flights/mela/csha/17…
Beijing:
https://www.skyscanner.com.au/transport/flights/mela/bjsa/17…
Changsha:
https://www.skyscanner.com.au/transport/flights/mela/csx/170…
As mentioned most days seem to be cheap in March/April. This deal seems to include almost all Chinese cities that CZ fly to. Not sure on the end date.
One thing worth noting is that if your stopover in Guangzhou is longer than 8 hours (I think), China Southern will give you a free hotel. I booked MEL-PVG with a 12 hour stopover and then went on the China Southern website and confirmed my hotel immediately.
https://static-ssl.businessinsider.com/image/56b25f6e2e5265b…