Tengah Chum:
I am down here on a retiree visa. I was required to show satisfactory medical insurance
BEFORE they would issue the visa.
At that time, (last year), MedibankPrivate were the only large health Insurance company in Australia who would issue cover acceptable to Australian Immigration dept.
BEFORE I physically arrived in Australia, (nearly a Catch22!).
There may be others now.
MedibankPrivate, GPO Box9999,Melbourne, Victoria 3001.
also at:
http://www.medibankprivate.com.au
Cheers and good luck,
GK