You're probably best not comparing the market here to the US market. It's a completely different animal, with scale being only the most obvious point of difference.
It's the same with just about anything: why can't we get motorbike parts for US prices, or books, and so on. With US postal charges so high now, buying out of the States is often not an economical solution either (assuming they'll even deal with an Aussie buyer)..
It's just the way it is. The best deals are on Silverstackers, no doubt.