www.abebooks.com
This is used book website. Enter "Gesner" and then the entire title and check 'hardbound'.
The low price result I found was a Random House edition for $20 + 4 shipping.
However, I think there was a mass-market paperbound edition as well from the 60s, but I am not sure if the one indicated as published by Jeremy is the script or the vocal selections or what. The photos don't give a clue since they are stock pictures of the original artwork. There is a feature, "Ask the Bookseller" but that could take a few days.
Jon is right. The revised script from the 90s has never been commercially published, and I have read that it is the version that is leased from Tams these days.
"If my life weren't funny, it would just be true. And that would be unacceptable."
--Carrie Fisher
