This is an awesome amp, you can even run it at 0.5 ohm, a buddy of mine has this with a pair of rf power series subs and they pound. This amp is a beast, to the guy saying this amp was sold for less, even on futureshop's site the 650.2 is selling for $499.99 so no way in hell this was selling for that low. I can vouch for that since i use to do installs at the stock yards locations a few years back. Open box items only sell for 10-35% less that of regular.
Good luck with the sale bud.