If Dunn didn't have a September worthy of 2011 we may have had a shot at trading him. I was hopeful at the end of August, he put together a really good half of a season in the middle of last year, and if he just kept that going through September someone would have wanted him.
From June 1st to September 1st he hit .272/.381/.498 with 18 HR and 51 RBI, and there are very few teams that doesn't help. Unfortunately, you can't follow that up with .159/.237/.348 for the last 21 games and maintain any trade value if you have Dunn's track record.
I think our only real hope of trading him is another run, straight from the start.