That model is considered by many to be the best 686 around: factory drilled & tapped for a scope, but still using forged hammer/trigger. If it's a seven-shot model, it's even better; S&W only made the 7-shot 686-4 for one year before moving to the MIM hammer/trigger model 686-5.

That's a fair price for a -4; even fairer would be $450 out-the-door =)