BOONE, N.C. — Freddie Pell helps lift a vintage wooden chair off the sidewalk and back inside his art gallery. It's starting to rain in downtown Boone, and he doesn't want it to get soaked — again.

In the elevator of the uptown gallery Lévy Gorvy Dayan, which is cramped with staff, an art handler issues a sheepish but firm warning to the art dealer Mary Boone: “There’s a Warhol behind you.” He ...