Brilliant little set of easels. If you were closer to home I could offload that very easily.
I have a commercial version called the Jobo Vario format easel. I use it extensively for doing various configurations of 8x10" paper.
With 135 format it is brilliant as a 5x8" which effectively takes a full frame 35mm film print. With 4x5" format I can do same size or slight enlargements.
I once had another metal version which had 6 plates like yours, somehow I lost it with one of my moves.
I do think you are probably wishing for a bit too much, something like $20-$25 seems to be more likely for a quick(ish) sale but given enough time you should be able to move it.