Personally, I don't see either console selling for less than $450 for the "cheap" model. I expect Microsoft to offer a 250GB drive and Kinect included. I expect Sony to also offer a 250 GB drive.
MS will most likely have a premium model with a larger hard (500GB?) drive (specifically since they said the built-in drive is not replaceable). I expect this unit to sell for $500 or $550.
Sony will most likely offer a premium model with a larger hard drive (500GB?) and the new PSEye. I expect this unit to sell for $550.







