This article is from the rec.audio.* FAQ, by with numerous contributions by Bob Neidorff others.
There is a "Blue Book" for used audio equipment called
"Orion Blue Book-Audio". This guide lists both a
wholesale and a retail value for most audio gear.
Orion Research Corporation
1315 Main Avenue Suite 230
Durango CO 81301 USA
Last I knew a guide costs $169. Each Nov, a new book is printed.
After June, the old book is discounted. If you need a single
quote from the Orion Blue Book, send a polite request to:
and you may get a quote back by e-mail.