I have a Glock 20 that with an aftermarket long slide. The barrel is Bar-Sto (I assume they made the slide too) and the rear sight is Bo-Mar. The gun is in really nice shape, but I don't really 'need' it. Since I took the gun in on a trade, I don't know what a fair price for the gun would be. Can anyone give me an idea of what this thing would sell for?