Bioshock 2 still sits on my shelf unopened after nearly two years I would guess. I have not played the first game in the series and was not really interested in Bioshock 2 either. But I remember that quite soon after it's release the price on the game plummeted.
I'm ended up picking the game up for about €3 on one of Gamestops Madness sales. I do wish they would bring back those offers.