You already have the background information from the Singer site- as for selling Ebay seems to be the way or if the local 4H has a yearly sale you might want to try that. You might want to plug them in and see if they work, do they need cleaning, how the wiring is ? Price values depends on what part of the country you are in , if they work, are they complete ( foot pedal , wiring ok, accessories, case condition, bobbin case) So many factors to consider- have you thought about maybe "awarding " them to a Grand Champion sewer ?