If you are cozy with your local farm equipement dealer he can provide you with a book very similar to the "Blue Book for Cars" which details average worth of all makes of equipement of varying conditions. Some dealers will readily show you the book while others guard it closely ( as they dont want you to know how bad they are screwing ya over when you trade a piece of equipement lol) Try asking your local dealer if you can see the book, its worth a try .