The major problem is that there is such a huge discrepency in prices. I pre-ordered Destiny for $55 delivered from an Aussie retailer, while at EB games its $99. Anyone that actually pays EB's prices is insane, but that is close enough to 50% difference.
Big W and other store slike that normally sell games on day 1 for close to cost, as they are banking on you buying someonthing else instore with a much larger mark up.
Add to that the famous Aussie Tax that has been mentioned. GST (tax) aside, we get ripped majorly on all software.