I have two:
The best assembled gun was a Dan Wesson 715, in near mint condition, in the original box, custom sights, with 3 grips, the wrench, and a pistol rug, for $269.
My all time best deal, period was when I went to a gun shop that was closing up and there was a box with "Dan Wesson parts" on it. It was heavy, and I asked, without even opening it up, how much did the old guy want for it. He said "$50!" I handed it over without even a second thought. When I got out to my car, I opened it up and I had hit the jackpot. While parked at BK eating lunch, I took the parts in it and assembled a complete Model 15-2 that I later sold for like $300. I had almost every part needed to make several more, less the frame itself, a bunch of barrels and shrouds, and a half dozen grips. I kept enough parts to fix two guns, along with 2", 4", and 6" barrels and shrouds. I sold all the rest and made about $600 profit, not counting the gun I had put together! I kind of think that's a once in a lifetime deal.