First, let me say NFI and that I know next to nothing about Gibson mandocellos.
I was in More Music in Santa Cruz this past weekend. The owner, Dave Handloff, spent an hour showing me many cool instruments including several Gibson tenor guitars, lots of teens and 20's A's, F2's and F4's, snakeheads, etc. it was a great way to spend an afternoon. One item that may be of interest to Cafe readers is this Gibson mandocello. I don't recollect the date but I'm sure some of you experts can chime in. It's not perfect, and it's had some work done on it, but the asking price of $1,900 seemed very fair. If you're interested, here is the contact info for the shop:
512 Front Street
Santa Cruz, CA