Call local shops in your area and see what they will ask for them (realizing they will be asking a little too much. Then check out the CLOSED auctions on GunBroker, GunsAmerica, and Auction Arms to see what they are actually selling for on the internet. Compare your local with that, and you should be able to arrive at a fair price. Depending on how fast you want to sell it, you will alter your price accordingly
For an upland gun of the pump variety, the Ithaca is a great light gun