Hi Bobbie, you can certainly search the auction sites even if you choose not to sell there in order to get a good feeling of the actual market price at the moment. Books and other printed research material will only give a historical (and often unrealistically inflated) view of the suggested value. Value is, after all, highly subjective.
You also may need to take into account the speed with which you wish to sell the item. If you want a fast sale, you will need to price accordingly. If you price at the top of the published prices, you may have to decide that you are happy to hold the item for some considerable time until a collector comes along who needs your piece and has been looking for ages and is happy to pay your price.