Isn't it worth exactly what you can sell it for. a few ways to do this.

slow and awkward, best market match: The auction. sell to highest bidder.

faster and more customer friendly but poor market match until a lot of units sold: The store. guess price, adjust up or down to reach sell frequency desired.

fast and good market match but takes a knowledgeable customer base: The reverse auction. Start with price too high lower it over time until it sells.