Dallas isn't giving up a first rounder for Jason Taylor, nobody will.
That's not true, and it's really not appropriate to write what you wrote as though it's a fact.
I don't believe you've talked to all 32 GM's in the league and asked them that question, and even if you did you can't really believe their answers.
The Jaguars could trade their 1st, they're built to win now.
The Giants could trade theirs if Strahan retires.
The Packers, Steelers, and Patriots are also teams that would be interested in trading for him. (Although the Pats wouldn't give up #7 overall for him, but the value of the overall package would probably be similar to a late 1st rounder)
There isn't alot of depth in this year's draft for pass rushers....most of the guys who will be available late in the 1st round are going to be gambles, you can't be sure they can contribute this year, and if you're built to win now you take the sure thing.
There are teams already offering a 1st and 3rd to sign Jared Allen to a truckload of money.....granted he's alot younger, but the team that doesn't get him would be very interested in Taylor.