1 TB RE3: 48 USD[0]
1 TB RE4: 53 USD[1]
1 TB Green: 52 USD[2]
That's the cool thing about the RE line.
[0] http://www.amazon.com/Western-Digital-Cache-Enterprise-Drive...
[1] http://www.amazon.com/RE4-Enterprise-Hard-Drive-WD1003FBYX/d...
[2] http://www.amazon.com/Green-1TB-Desktop-Hard-Drive/dp/B006GD...