MSRP is $638. and 100% is $460.
I find that Gun Broker is a great source for current gun values as it reflects what the market for firearms is currently bearing. If the market is inflated with a certain firearm you will not pay Blue Book prices, supply and demand.
Furthermore, a gun values really comes down to whether you are buying it or selling it. How much do you want the firearm opposed to how much the seller needs the money.
God, Family, Guns, in that order.