Medical treatment in Australia is very expensive if you do not have the proper health cover medical insurance. Being an International student it is your responsibility to have a valid Overseas Student Health Cover all the time to avoid any visa issues. It is one of your student visa condition to have a valid Overseas Student Health Cover in Australia.
These are some of the Overseas Student Health Cover providers which offers health insurance in international Student studying in Australia
Medibank
Bupa
nib
Allianz Care
ahm OSHC
CBHS International Cover

It is recommended to shop around to get a good deal. You should write an email or give them a call if they have any special price to benefit from.