Cabela's has a Leupold Vx-2 Canadian, 3-9x40mm on sale for $300, usually $400.
I have had the Vortex Diamondback and this Leupold. Nothing wrong with the Diamondback, but the Leupold, IMO, and I speak from experience, is a much better scope as it offers you the ability to go down to the gun store and pick up a CDS Turret for $40 that is designed for the ballistics of common 30-06 ammunition. It works very well.