Hi there. I just found two 1979 Kilncraft mugs (Fozzie and Rolf) whilst helping my boyfriend move. I remember having a Miss Piggie one (which sadly got broken) as a child and am loth to throw them out. Does anyone know if they are worth anything? I love the vintage look, but we will run out of space soon so I'm not sure if should hang onto them for a few more years or not? If anyone know anything about them, I would be very grateful.