Bud's Gun Shop has the S&W M637 for $418.00. There will be some fees for your local FFL to receive the gun, but you still get a $50.00 rebate from S&W through the end of this month, so you should come out under $400.00. I really like the little Smith and I don't have any hangups about it being new. Smith's bad days were in the later 1970s and 1980s toward the end of the Bangor Punta era, so used is no guarantee of satisfaction.
Of course, everyone is going to jump up and down about the M637's exposed hammer. Because of the way I draw the gun, I don't have any problem with it snagging, even when it's in a pocket. If it's a big deal to you, Bud's has the M642 for the same price.