Boy, I wish you'd placed this add last week! I was at an estate auction this past Saturday where the guy was a big fan of the little mini-Graflex cameras. There were holders and a stack of these developing hangers. I bought a couple of larger sized contact printing frames (3 1/2 x 5 and a larger one,) but as I recall no one wanted the developing hangers. As far as I know, they were still laying on the table when I left the auction. They probably threw them out. Sorry, I know that wasn't what you wanted to hear!
Life should not be a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside in a cloud of smoke, thoroughly used up, totally worn out, and loudly proclaiming– “Wow! What a Ride!”
I've seen them show up on that auction site fairly often. I bought about a dozen 3-1/4x4-1/4 developing hangers in the last 6 months. I think that there were a few 2-1/4x3-1/4 hangers mixed in. A little patience goes a long way.