I'm with John Wayne. $420 is a good price for a 642. I'd buy it.
I have a 642 and it's been flawless. It also operates and feels just like other S&Ws, so it doesn't matter if I'm holding a 642 or a 629, I don't really have to think about what I'm doing when I load it or fire it. My wife can play around with my old Model 10, and the practice applies to the CCW gun. If you have no other Smiths, that's not a real issue.