Good show on PBS
 

There is a PBS series for music (production) junkies called
Soundbreaking.
They are talking about how music producers and technology has changed
music. I just finished episode 2 where they talk about multi tracking
and how it was invented by Les Paul (best represented by "How High the
Moon"). He and Mary laid the whole thing down on 2 track tape, laying
one layer over another until it was something like 8 part harmony.
Then my wife asked a question "how much does a run of the mill genuine
Les Paul guitar go for"?
I figured Tim or Richard would be the best source for that kind of
thing.