I hate to rain on the parade here, but there are some things to check on one that's available for that price. The trigger could be 'floppy' (back and forth) if the trigger return spring is broken. Unlikely, but it could have a cracked frame so it pays to look closely at the frame. No matter what, I suggest that you ask to pull the slide which will make it easier to check out. Speaking of slide, and this mistake cost me over $100 last year - check to see how much vertical play the muzzle end of the slide has on the frame. I bought one that was so loose it would shift, on the frame, by just turning it onto it's side. That was a hard lesson - but someone bought it at a great price for a truck gun. Also, I have not seen this but heard about it; check the two frame 'wings' behind the magazine well as one could be cracked, or worse, broken off and gone. Folks get carried away driving the mounting pin when changing grips and break one of the wings off.
Don't get me wrong, I like them very much and they're the best metal-framed auto S&W ever made IMHO. I have a near-new 3913LS, a refurbed 3953 (Thanks to BMCM) and recently an as-new 3913NL. I am always looking for another but it pays to check them out closely.