Re: Bank of America Traveler's Checks Posters (1978)
Nagel did TONS of advertising work, for a lot of large and small clients. After all, he was doing ad illustration for close to ten years before he met Karl Bornstein, who started him on the "museum quality advertising" collectibles path. As such, most of these posters were lithographs that were printed by the truckload.
That doesn't mean these aren't collectible for their content. And if Nagel's work continues to escalate in value, it doesn't mean that even his lithographs might increase in value. After all, Alphons Mucha's lithographs sell for thousands today.
That having been said, I agree that at this point, $450 seems a bit pricey for these posters -- unless you love looking at them, which is totally fine, too.