Went looking for the OW Seagate 640GB $88.17 without luck, but did find the Acer mentioned in the comments.
The Acer model AH002S has a USB connection and a WD WD6400BEVT drive inside.
I asked the cashier how long they were on sale for but she didn't know, Harvey Norman Watergardens had 10 left this afternoon.
best value for money 2.5" portable atm if you can find one @ ur local HN.. otherwise get the 1tb seagate from online computer for $135 delivered