If you are going to the one in Dulles, go see Dark Sun. You won't find a cheaper price from a vendor. Remember you need a VA D/L, a second form of ID, and a birth certificate/valid U.S. passport. You will hear lots of different opinions about Dark Sun, but when I buy, I know what I want, and I don't need to engage in needless conversation or try to barter them down on price.
I haven't found anyone selling for cheaper. Last show in Richmond they were selling .223 Saigas for less than 300.00.