What do I look for in used records?

To add a little bit more to the above posts, the first mass produced stereo recordings were available in the late 1950's. I believe they were predominately classical releases (someone correct me if I'm wrong). The collectors go primarily for the RCA, Mercury, and London records (from this era). As for identifying the stereo versions the RCA's are of the LSC-xxxx series (Living Stereo) and the Mercury's are of the SR90xxx series (Living Presence). I'm not so sure about the London's, I know the early issues are identified by their light blue back (of the jacket), but I don't know if they are all stereo. As for the mono releases, the RCA are identified by LM xxxx and the Mercury are identified by MG09xxx. With respect to the album Wdi found, it is a mono and probably predates the first stereo releases (1957?).

Pmotz...I believe that the first release of a stereo record was a Dukes of Dixieland LP from Audio Fidelity. I don't have that very first issue, but I do have several other Dukes records that they issued in the months following. The audio quality of those first records was better than 99 percent of the LPs that have come out since. Audio Fidelity, before the advent of stereo, had already established themselves as an "audiophile" label (as the name suggests). I don't know if today's Audio Fidelity outfit has any connection with the old one. I have been unimpressed with their recent work.

Eldartford- Thanks for the info, I've seen Audio Fidelity records over the years but never bought/listened to one. Sounds like I'm missing something good!