I saw a 6 month supply on eBay just now that you can import into Australia, but it depends upon how much you want to pay for it.
Check it out - use 'Rogaine Foam' as a search phrase.
This is how I bought my 3 month supply a few days ago...otherwise I don't think it's available here yet.
(The Buy-it-now price plus postage comes to $123 for 6 months worth.)