This article is from the RCA SelectaVision VideoDisc FAQ, by firstname.lastname@example.org (Tom Howe) with numerous contributions by others.
There were quite a few CED liquidators back in the late 1980's, but I am
aware of only two that are still active:
Mail Box Video
19050 Middlebelt Rd.
Livonia, MI 48152
This company deals in CED and other video formats, and currently has a
listing of a few hundred CED's for $5 or less per title (they also have
periodic sales). They have multiple copies of many of their titles, and
will trade 2 for 1 on titles they don't have. All the titles come
shrink-wrapped, usually with a $29.95 price tag, but this is rarely the
original factory shrink-wrap, since on most discs you can see marks on
the caddy underneath the shrink wrap, and some discs, on inspection,
reveal fingerprints. Still, the quality of their discs is roughly on par
with discs I have gotten from private collections.
2342 North Dodge
Tucson, AZ 85716
A giant used record store that also carries a large stock of CED's. They
have a web page at the above URL, where you can fill out a form
requesting CED titles.