I by no means wish to rain on your parade or belittle your fine gun but the PowerPort 686s and 629s were not exactly popular, thus their discontinuance. While I have not followed their prices for about a year, $600 would buy a very nice used one at that time.
I have an unfired 6" 686-4 PP for which I paid $650 during 2010. I also bought a dirty but otherwise nice used 6" 686-5 PP in 2011 in order to get an S&W I wanted from a seller who would only sell the two guns together. All of them were purchased on GunBroker, so I was bidding against other people, not finding someone who didn't know what their guns were worth. Two photos of that -5 are below; after giving it a good cleaning, I sold it for $550.
Again, I mean nothing adversarial; just trying to offer some friendly advice.
Ed
Welcome to the Forum, by the way.