The 642 and 442 (the black finish version) are still available without the lock. Based on the grips (from what I can tell in the picture) they appear to be the current factory ones with the S&W logo. If they are that style of grips, then the gun is fairly new (assuming they are the original grips) and you did "okay."
My LGS sells that gun NIB for about $399 O.T.D. including the $10 for the state background check. The biggest question is how is the trigger? The last two j-frames, I bought had TERRIBLE triggers and left me very disappointed.
If you like the gun that's all that really matters in the end. If you aren't too impressed with the trigger, an aftermarket spring kit can help improve it dramatically.