Well, Bookfinder (click) says there's one for twenty-five bucks at Brass Dolphin Books, 1619 N Fifth Street, Boise, ID , U.S.A., 83702-3706
Phone 208-345-9041 / Fax 208-345-9041, Email lhavens@cyberhighway.net> I'm not sure a link to my search will bring it up for you, but I'll try:click here. If that doesn't work, go to Bookfinder and search for sing out collected reprints.
I think it's the correct book, but you'd better check to make sure. The one that's out of print is the pink book, published in 1990, is Volumes 1-6, 1959-64. The blue book was published in 1992, Volumes 7-12, 1964-73.

I was just about to walk out the door of Moe's Books in Berkeley, CA, yesterday, when I noticed a cart full of used songbooks that the store had just received. It cost me $177.91 by the time I got out of the store. Unfortunately, another guy saw the cart at the same time, and he got the Weavers and two Ewan MacColl songbooks. Seemed like a worthy sort of guy, though. I gave him Mudcat's URL and told him he was responsible for MacColl songs. (grin)
-Joe Offer-