swmetal,
From what I gather, a pistol likely to be the one you are looking at was once owned by a Forum member who described it in 2010 as a "170105 CQB proto with front NS". He did not give the serial number, but the product code and the fact it was a prototype correspond with the pistol identified by Earl as PCZ 0186, a 4566 CQB all stainless model of which 91 were made.
The photo our member provided no longer exists on the thread, unfortunately, and since that member has sold some of his collection of Performance Center pistols, what you are seeing could likely have been part of his collection at one time. I would guess it looks very similar to the one in member wlp624's group photo posted above, on the right side of the picture. I also would guess that it does not have the "45 CQB Performance Center" banner on the left side, and instead just has "Smith & Wesson, Springfield, MA, USA" on there.
IMHO, a pre-production model doesn't have a premium attached to its value except to the extent the rest of its series is worth a premium due to rarity. Since the 4566 CQB all-stainless finish was only 91 units, and since what you have is basically that pistol, yours should be worth whatever the others are. Just my opinion; an extremely serious collector might pay more, but how much is anyone's guess.
The 4566 CQB stainless pistols, in my opinion, are worth a bit more than either of the 4563 CQBs, and less than the 4566 CQB with blackened slide in all stainless, as only perhaps 20 of those were made.
Depending on condition and what comes with it, I'd guess PCZ 0186 is worth in the $1,500 to $2,000 range to someone who knows what it is. Hard to nail it down any closer than that, though.