I was browsing the web last night looking for reviews of Windows Defender and came across a link for Bitdefender Antivirus which is selling it for $5.95. Great price.
I am not sure about the website. Never bought anything from them. They also have a Paypal option which might help if there are any issues after the purchase.
The official website has it for $59.95 http://www.bitdefender.com.au/solutions/antivirus.html
It has got very good reviews
PC MAG: http://www.pcmag.com/article2/0,2817,2406906,00.asp
Cnet: http://download.cnet.com/Bitdefender-Antivirus-Plus/3000-223…
This may be a good option for people who prefer 3rd party antivirus programs over Windows Defender.
Pity this doesn't work any more :( http://www.ozbargain.com.au/node/61390