There are two different species in your photos. The mostly orange and dark grey fish is a clarion angelfish (Holacanthus clarionensis). The two fishes with blue markings around their eyes are conspicuous angelfishes (Chaetodontoplus conspicillatus). The reason for the high prices is no doubt because they are relatively rare in the aquarium trade. They both have fairly restricted distributions: H. clarionensis is found in a narrow part of the eastern Pacific (Clipperton Island, the Revillagigedos Group and the southern tip of Baja California) and C. conspicillatus is known the cental part of eastern Australia (southern Great Barrier Reef to central New South Wales), New Caledonia, Lord Howe and Norfolk Islands, and Elizabeth and Middleton Reefs in the Tasman Sea. Much of the range of the latter species falls within marine parks.
Tony