The good old internet. I bought a whole bunch of Red Diamond (Kamagra) Jelly from the Internet at £2 for each 100MG Sachet. £50 for 25 sachets. I am sure that this is possible in Australia... You just answer yes to all the questions and say that you are super healthy and very fit etc.
I did not see Kamagra much cheaper than this in Patong.
http://www.kamagra-man.com/
Mac