PricePal cashback makes it cheaper than the £184.85 deal posted by lyl only a month ago. Cheapest local stock is $405 @ MSY.
The 500GB is pretty good too as it's $205 from MSY.
Choose GBP as the currency.
Also use either 28 degrees or Citibank to pay for it. I think Bankwest is good too? But not 100% sure.
EDIT: at least 7.5% cash back from PricePal which equates to £7.52 and £14.55. Thus bringing the total spend to be about ~$157AUD for the 500GB and ~$303AUD for the 1TB. Use a random referral if you don't have a PricePal account yet to receive $5 on signup (minimum payout is $20).
Mod: Price after cashback (commission-refunds) removed from title. Cashback tracking, approval and payments are not guaranteed.
Tempted for another 500GB. Bought one recently at $180, and it made my 2012 MacBook Pro like brand new!