It's tough to know the EXACT dealer cost of a gun. The dealer could have gotten a bulk deal or have just been in the right place at the right time to get a great deal on something. Or the dealer could have bought the gun a year ago before the big price jump. I like to read through Shotgun News often. This is the same place that many dealers get their stuff from!
By reading SN, you can get a pretty good idea of a gun's current value. However, I have bought a few guns under what SN lists them for. These are prob old inventory. (I love these buys!)
I like to buy a Shotgun News when I walk into a gunshow. Then I keep it tucked under my arm as I shop. The dealers recognize this and usually don't give such absurd first price quotes.
HTH!