I'm looking at a Glock 22 with a Zev trigger group, stainless frame pins, stainless extended mags release and frame stippling all done by Zev. I'm wondering how much this could add to the cost of a private sale. It's a gen4 series, very lightly used coming with 3 mags. This is being offered by a friend of mine who is in a bind. He's making me an offer of 400, and that seems low. He won't take more just because I offer it. The sale needs to be fair for both people. Is 400 bucks too low? Seems like it when I price the upgrades on it.