That's just it - the Cards need to ensure that if they're serious about this, that they find out from every NFL with interest what Boldin is worth, and milk the living dogsnot out of it.
Boldin is a PROVEN #1 WR. Those don't grow on trees. Everybody knows that it usually takes a couple of years after a WR is drafted for him to truly know how to play the NFL game - Boldin's presence on another team solves that problem.
Personally, I'd like to see the Cards end up with a pick in the Top 15 if they have to let Boldin go, and get Knowshon Moreno. Clearly, multiple picks are warranted, and a ready-to-play player would be nice as well, if possible.
We all know we need a RB, and while I really like Beanie Wells, i think Moreno is a serious difference maker, and with the amount of space with which he could work with the way defenses have to play Warner and Fitz, Moreno could be a ROY candidate in AZ, and be a major piece of a 12-win team.
In short... if there's a way to pawn Boldin into getting Moreno plus another pick or 2, that's got to be the first consideration, IMO.