It is a one of a kind kit, so the price doesn't shock me. I can recall paying a similar price for limited edition passenger car kits. In this day and age, where wheelsets are over $1 per axle, and a pair of truck frames can cost $12 (or did, when shapeways was still operational), and a mass produced Bachmann passenger car is $60 MSRP... well, it is what it is.
Not really something I have any use for. But glad I know it's out there. I had no idea the prototype existed. When I saw "Stilwell Oyster Car" I was assuming it would be an arch windowed observation or private car or something, not, literally, a car for hauling oysters to Kansas City.