The posters are wonderful and probably in very short supply. That's the good news. The bad news is that they're not in the best condition and not worth any cash money: lots of creases, folds, and wear. Also, these are very likely commercial lithographs, because after all, they were printed for commercial use. All that having been said, in my opinion, there's an outside chance that someone might want them as part of a retrospective collection to show the breadth of Nagel's career beyond his fine art collectible work. Remember that Nagel did WAY more commercial illustration than fine art and that a lot of his collectible work was destroyed or damaged by those who didn't knw what they had.
One more thing: Always store your work flat, not rolled. It's much better for the piece, no matter what kind it happens to be.