Karlsson's keeper value has been taken down a notch in my books given the uncertainty now about whether he'll ever be the same again.
Having said that, if I were to trade him to shore up my defense, the only guy I would accept coming back is AP+ so you're on the right track (sorry Letang fans, but he's joined the skeleton squad in my books).
I'd aim for AP + new keeper upgrade. So AP + someone better than Staal or Subban. With Anderson out, you may want to think about shoring up your goaltending too, but we don't know how serious it is yet... just something to think about.
2013 Bay Street CBS Playoff Cash Pool - $100 buyin
12 Teams, Points Only (G/A = 1, DG = 2, W = 2, SO = 1)
The Motherpuckers (5 NYR, 2 PIT, 3 VAN)
Forwards: Neal / Iginla / Nash / Richards / Stepan / Roy / Higgins
Defense: Del Zotto / Garrison