I've bought and sold I don't know how many guns, some, many times over. Not the same actual gun, but the same type. The only ones I really regret selling are...
(1) AYA SXS double 20 that I got from Sears/Roebuck about 1979 or 80 for less than $200.00. Beautiful little gun. Stupid of me to sell it.
(2) 1964 Colt Python, Royal Blue, with a 4" barrel. Had to sell due to "personal economic downturn." I tell myself it was Ok because it went to a young Marine just back from Iraq.
(3) 1953 Smith and Wesson "357" (a pre-27) with a 5" barrel, stocks numbered to the gun, and the numbered to the gun blue/gold box it came in.
(4) Smith and Wesson, Model 39-2, 9mm, in blue. Unfired outside the factory (I believe) in the box, with all the accessories. Same reason as number 2. Personal economic downturn.
(5) Not one, but TWO Smith and Wesson Model 24-3's (44 Specials) both with 4" barrels. One of them was in the box, with all the accessories. They only made something like 2500 of them, and I had TWO. No excuse. Just stupid.