Century Symphony Orchestra, Waltzes by Johann Strauss, Jr. (1956)
Just note, classical music is definitely going to go on forever. Music labels typically employ obscure musicians for their albums to create the album covers. Since the singer went on to be a major celebrity, the album is unique. None other than Andy Warhol was the person who produced this album cover! They discovered just 7 copies of the ledger. At the Museum of Andy Warhol, while in 2012, the other one went for $5,500.
Century Symphony Orchestra, Waltzes by Johann Strauss, Jr. (1956)
Max Steiner, The Caine Mutiny
This album was a half-dialog, half-soundtrack. It was scrapped after novel writer Herman Wouk decided to avoid having the studio use his job again if they published the record. He was furious when he saw the novel lifted verbatim. That was why he and Columbia decided to avoid the release and delete all the copies they made. However, some workers preserved several originals. One edition went for $6,700 in 2007.
Max Steiner, The Caine Mutiny