I just bought a pair of them on a farm auction last fall, one had the cast iron packer wheels the other didn't, one is rope trip and the other has the manual lever lift. Mine are both 10ft and have the small seed boxes and in pretty decent shape, haven't been used in a few years, but are in decent shape, and stored inside, but missing some of the spiral metal seed tubes and the things that mount them to the meters. But I know where theres a few of them in a junkyard. Paid $300 something for one and $180 for the other.
When I finally get around to working on them, it shouldn't be too hard to get them loosened up again. The plan is to take one and cut it in half to make a pair of drills to pull behind a 4 wheeler or side by side. The other one will get made into a 3pt mount and be used to explore innerseeding cover crops into our cash crops.
I talked to a guy who buys and then builds them into smaller ones like I'm doing, found him on the internet. He said 10fts like mine are worth $1000-1200 in good condition. I figured if nothing else I can sell mine to him. If its decent shape and everything is there, parts aren't too much of a problem. I think you can even get some from JD new.