The thing is, it doesn't matter. As far as I know, nobody prices anything in Bitcoins, they price things in USD/AUD/ and then convert that amount to Bitcoins for the transaction . You might end up paying 1.00 BTC, or 0.6 BTC, but it still works out to the be same in USD/AUD/ (numbers made up for example)
Who's handling all the instant real money conversions, and why wouldn't they just transfer the real money between accounts directly rather than converting it?