Duke McCaa (owner of the Pistol Parlor) once told me (when I was quoting blue book values) "That's just somebody writing a book. They aren't out here trading guns everyday".
Look out on GunBroker, Armslist, AuctionArms, etc. and find some similar that have sold. Then you will have your value, what somebody is actually willing to pay.
you CAN'T look at asking prices, you MUST go to the sold page AND SEE WHAT THEY ACTUALLY SELL FOR, NOT WHAT SOME PUTZ IS FISHING FOR!