It's difficult to answer this based on what Letang "wants". Because I'm sure what the Penguins "want" is not the same number - and if they agree, it will be somewhere in the middle.
If the Pens trade Letang, we'll need someone to run the powerplay, and that won't be cheap either, if they are good. (unless we try Martin first?).
It's most definately a long-shot, but I'd rather the Pens try to sign Letang at a more friendly cap hit, and work on his PP and consistancy - because just about everytihng else is special, and he eats a ton of minutes as others have said. He's just coming into his prime as well.
They have to get Geno done first though before they decide on 58, I think.