I had one of the earlier 681 PC Quadraport revolvers, and the revolver was a mixed bag. It had some really nice features, including the seven-shot cylinder, the three-inch barrel with the full-length ejector rod, and nice fixed sights. Unfortunately, the PC action was pitiful with the strangest issue being that the overtravel stop did not contact the triggerguard, meaning it was useless. How that made it out the door I do not know. It also had the worst feeling trigger of any S&W I ever tried.
I still purchased it, hoping lots of dry firing would smooth out the action and not really needing the overtravel stop. Then I learned it shot about six inches to the left for my eyes. And it shaved lead and spit.
At that point, I was done with it. I sent it to S&W, got it fixed, and sold it to a buddy who is a collector.
My lesson: Do a better job of checking it out than I did. If it looks good, $700 is a fair price. On the other hand, you can find a four-inch 681 for about two-thirds (or less) of $700. That is what I did when I purchased an old Atlanta PD 681-1. That gun was not pretty, but it was worth the $300 I paid for it. And it shot to POA with 158-grain JHP.