Hi merlinmagic
I've been subscribing through the UK site for some years now, there are a number of reasons for the difference, firstly the exchange rate has changed dramatically over the last few years, it is not that long ago that 1 Australian dollar was worth 40 UK pence, now it is worth 64 UK pence, also we don't get charged VAT or GST, and then there is the traditional thought by overseas companies that Australians should pay more. But it is not just subscriptions, I've a book on its way from the UK, it is less than half the price than purchasing the same book here, and even if they started charging GST it wouldn't make much difference as it would stll be nearly twice as dear here.
Andy