They're constantly sold dirt cheap in my area with very minor problems, like old gas. People don't know how to fix it, so they buy a new one and sell the old.
I bought four working mowers. $500, $250, $220, and $200. One was missing a deck, one was running rough. Otherwise complete.
They're all craftsman, one vintage from the 80s.
We use one to mow, one to move the trailer, the old one mows but it mostly sits, and the last was a gift for my wonderful neighbors who are old and were still using a walk behind.
Stuff goes straight to permanent memory at that age so by giving them a "real" tractor there's a lot of potential to learn good lifelong lessons prompt them to ask the kind of questions that result in good teaching.