Welcome to Mobile Read
Harvey Norman is selling the iriver story for about $400.
You can buy Sony from B&H Photo in the US and they will ship to Australia.
DA Direct in Melbourne sell readers.
Keep trawling through these fora (forums?) and you will surely find plenty of information to help you make a decision.
I just purchased a Sony PRS-900 on ebay and had it shipped to Oz.
Good Luck.