If you are in the U.S. it is a rare bicycle. If you're in europe not so much.
$50 would be a bargain for them, but then again even cleaned up I think you would be lucky to get $100-$125. At least from somebody who knows bikes. It might be worth more for somebody who just wants a weird bike, but from a objective point of view these aren't any better than say an old Raleigh so about old Raleigh value is what it'd be worth.