I like the idea of including the solo shorts, and having it as:
Volume 7, 1952-1954 (2 discs)
Volume 8, 1955-1957 + Shemp solos (2 discs)
Volume 9, 1958-1959 + Joe solos (2 discs)
OR (if it fits better):
Volume 7, 1952-1954 (2 discs)
Volume 8, 1955-1957 (2 discs)
Volume 9, 1958-1959 + Shemp & Joe solos (2 discs)
Or even still:
Volume 7, 1952-1954 (2 discs)
Volume 8, 1955-1957 (2 discs)
Volume 9, 1958-1959 (2 discs, split up one year per disc. I know they'd be relatively brief discs, but they could just run it for a cheaper price. May actually help sales at that.)
Just ideas...