The RCA recording with Copland conducting was the one I grew up with, I still listen to it. I thought I saw it reissued, maybe by Analog Productions, but I don't see it anywhere so maybe it's a possible future reissue. The originals should be out there in used bins, though. I note that RR22, mentioned by Folkfreak, is the original version for 13 instruments, not the full orchestral version. It is a different take on the piece, but a good one to have in the collection.
