Re: just venting
You live in the wrong place. Here in Minnesota nice-running Johnsons and Evinrudes from the 50s go for $200 and up, depending on the model. Folks here appreciate the old engines, and know that they can depend on them, once they're fixed up and running well.
Craig's list always has several for sale, and they don't last long, either. If you don't call within a couple of hours of the time the outboard appears on the list, you don't have a chance to buy it.
The most popular of the johnnyrudes from that period are the 7.5, 10, 15, and 18 hp models. The 3hp models also sell well as engines for the boat at the cabin. The Big Twins sell OK, too, but not as quickly. Of course, you can hardly give away a Fat 50, but that's an exception.
Anything from about 1955 up through the mid-60s, in decent cosmetic condition and running perfectly sells well. A double-line tank, though, has to come with engines that need it, or they don't sell. Those tanks are like gold here.
I fish a lot in the smaller lakes around here, and see the older engines all the time on boats out on the water. Guys are fishing with them every day.
I wouldn't buy and sell the things...too much work. But when I had my 1958 RDS-20 Johnson on the back of a crummy old trihull, a guy came up to me on the ramp and offered me $900 for it on the spot. We went to the bank in the nearby town. He got the money, and we moved the outboard off my trihull and into the back of his pickup right in the bank parking lot. Seems he had a 1958 Herter's fiberglass Fin Boat, and that was the engine he was looking for. Normally, they go for about $400 here.
Like I said, Missouri just may not be the place to sell the old-timers.