Hmm.. well, They only have 1 version of the GTX 660 and its definitely not the best one cooling/overclocking wise, I recommend going to the website I told you about before, But it depends what state your in? eg: NSW
gtx660/ti or 7870. http://www.msy.com.au/Parts/PARTS.pdf thats where you'll find the cheapest pc parts in Aus. Theres a cheap msi 660ti there for $239, that is your best bet. the cheapest 760 is over $339, and performs similarly to the 660ti.