RCA was the first record company to issue 45’s in both mono and stereo and the difference in value can be quite significant. In 1960, Elvis Presley had one of his biggest hits with “Are You Lonesome Tonight.” A mono copy, as seen on the left, is valued up to $20.00. Add up to another $50.00 for the picture sleeve a seen here. A stereo copy,seen on the right, can jump the value up to $800.00.