Theres 33% of heaps (most?) of their stock.
I picked up Cosmos by Giles Sparrow for $43 delivered; cheapest price using Booko was $54.63 delivered.
A lot of the prices now are very competitive with Book Depository. Using Booko as a comparison, sometimes Book Depository is still cheaper & sometimes its cheaper to just go into a Dymocks store to buy it, buy some good deals to be had there.
A tip: if you're trying to work out the price in australian dollars, you can search google eg "£5.35 in AUD" & it'll convert it for you.