Actually I think David Bowens is one of our more marketable players, and I have been thinking about this one for a while now. He's still young at 27 years old (about to turn 28 in July I believe), he's VERY athletic (often compared to JT when they do agility drills, remember when he was our best special teams gunner in 2001?), and he was productive when given the chance to start on a team that has a poor rushing defense and an attrocious offense (which means, teams were running the ball on us a lot, because it was easy to and because they were usually ahead in the score...evidenced by Miami having defended more runs than any other team in the NFL, while having the fewest passes attempted against them per game in the NFL).
When a team has poor run defense, and a poor offense that allows the other team to get a lead and run the ball to run the clock, that clamps down very effectively on possible sack production. Miami had fewer passes attempted on them than any team in the NFL. If you account for this, then Bowens did better in the sack department per pass attempt than guys like Chike Okeafor and Justin Smith, and even Jevon Kearse...about on par with Aaron Schobel, Steve Foley, and Joey Porter.
Bowens still has unrealized potential and I believe there are other teams that know that. His problems during the early part of his career were mostly mental. The guy was immature, spent irregularly, and ran into trouble. One thing you can't say since he's come to Miami, is that the guy has not been into it mentally. He's been tough. He has had his head in the right spot since he's been here. So, what you have, is a gifted athlete who was just waiting for the opportunity, had that opportunity stolen from him by a combination of injury and the ascendance of a pro bowl caliber DE Ogunleye, and in the season when he's had his first real opportunity to start, he outperformed guys like Kearse, Smith, and Okeafor.
I would not cut him. You always need DEs of that caliber on your roster. And, I wouldn't settle for anything less than a 3rd or 4th rounder for him in trade.