The value of Jim Beam decanters varies. To find the approximate value check on Ebay to see what similar items are selling for or have sold for. This price should be close to what yours is worth.
1 Additional Answer
What your Jim Bean Decanter is worth will depend on the type of bottle you have. The condition will also determine the value. Some decanters are worth as little as $15 while others are worth up to $50.