What have they offered you for it? The second hand Smart market is incredibly strong for all the reasons you mentioned here. The only exception is the 4-4.
It ended up being fairly easy to sell privately. But then again it was in really good condition with relatively low mileage. I think it's always worth trying to sell privately first, i wish i'd done that with my Clio. I'd happily entertain a couple of knobheads for an afternoon if it meant i got more for my car.