Welcome!
You have the options of using points, or using cash. In regards to the first option:
While I do not know of any JASA SC runs from MEL, have you done a search of the forum and looked yourself? There might be something already posted, and if not, you might have to consider a cheap positioning flight to another starting point.
On the other hand, if you want to use cash, there’s always the old faithful Fiji SC run starting in BNE (again you’d need to get there yourself, and back), that gives 360SC’s.