Most of the guns I've sold I sold with good reason and so I don't really regret it. At the same time I at least occasionally regret parting with all of them.
-Ruger P89. My first auto. It was a good gun but I didn't love it (a bit blocky), I wanted a 1911 and didn't think I'd have many guns and so I tradied it. I usually don't regret trading it, I wouldn't have bought my Charles Daly 1911 if I didn't and I love my 1911, but sometimes I miss it (nostalgia, my first auto, mostly).
-Taurus 82. It was a good gun and it was my first gun. Sold it because I didn't plan to own very many guns when I first got into shooting, I wanted a .357mag, and when I bought my S&W 65LS I didn't see the point of having two medium framed revolvers that could both shoot .38spl when I knew I'd only own 3-4 handguns :banghead:
-Mossberg 500. I sold it at a time when I was totally broke and needed the money more than the gun. For that reason I don't truly regret selling since I didn't really have a choice and it kept me from having to sell other guns I'd regret more, but I do miss that gun (I should have bought another Mossberg instead of my Benelli Nova). At least it found a good home with someone from TFL.
-Ruger 10/22. I bought it because everyone who had one loved it. It seems to be the most recommended .22 rifle. I wasn't particularly impressed and I like my Marlin 60 so much more. It was actually kind of boring. So, I decided to sell it and it found a home with someone else on THR (may have been on TFL at the time). Occasionally I think about picking up another for various reasons (it is more compact, there are tons of aftermarket parts so I could make it a project) but I never do.
-CZ 40B. I gave myself several excuses to talk myself into selling this gun. I wanted a carry gun for when visting a carry state and for if I moved to a carry state or MD became shall issue, but I live in MD which is far from shall-issue so it would be primarily a range gun. This gun was a smaller service sized pistol, so I sort of bought it as a carriable pistol which would still be a good range gun. Still, it was a bit big and definately on the thick side for CCW. Since it was alloy it was a bit light for the range. It was a compromise gun that wasn't ideal for either reason for buying. At least, that was what I kept telling myself. The real reason was that I just couldn't warm to the .40S&W caliber (and I knew then that was my main reason for selling this reliable and accurate pistol). I sold it to a fellow THRer. Well, today .40 S&W just may be my favorite defensive caliber and I really miss this pistol. I haven't replaced it yet though since the cheapest used 40Bs I've seen in decent enough condition are selling for as much or more used than I paid new for mine.:banghead:
-Taurus 605. .357mag in such a small gun was just too much and it was a couple oz. heavier than the .38spl Taurus 85. I wanted the lighter weight of the 85 if I wasn't going to shoot magnums out of this gun. So, I sold it and eventually bought the 85. Occasionally, I wish I still had it even though I'd very rarely shoot magnums out of it. I have the lighter weight 85 now and a lightweight aluminum S&W 442 and I already had the larger 3" K-frame 65LS. Sometimes I wish I had the versatility of that 605- j-frame size, lightweight (compared to a K-frame), yet still able to shoot magnums from time to time. Still, I sold that gun several years ago and I've only recently started having those regrets.
-Colt Police Positive Special. The gun never really grew on me. I guess I'm a S&W (and Taurus) revolver guy. So I eventually gave up and sold it. No real regrets, only that I could have sold it for more if I was more patient.
-Remington 581. A decent bolt action .22lr. It was near 100% reliable (if another of my .22lr discovered a dud round most of the time I could put that round into this gun and it would go off) and was very accurate. It was a good gun. But I didn't particularly like it. I gave it several years but decided I wanted something nicer. So I sold it to another THRer intending to get a .22lr CZ bolt rifle. I still haven't added another bolt action .22lr yet, but I will.
-Savage 110 in 30-06. Good gun but I didn't shoot it much (I don't get to the rifle range much to begin with and the recoil on this was stout). It wasn't my first choice in caliber, but I got too good a deal to pass up. Well, as said before, I didn't shoot it much. So, instead of adding a recoil pad to make it more pleasant I simply sold it (to a fellow THRer once again). My intention was (and is) to replace it with a gun (preferably from CZ, Howa or Wincester, but I'll certainly consider another Savage) in one of the calibers I really want (.308, 6.5x55, 7mm-08, .243, etc.).
-Hi-Point Carbine in 9mm. It was a fun and reliable gun, but it was only meant as a toy and I didn't use it that often. It also had a bad habit of hitting my face just right so as to be somewhat uncomfortable (a somewhat unforgivable trait in a long gun chambered in the relatively light 9mm). So, at a THR shoot one of the regulars liked the gun and I told him if he had a certain sum (I'm not sure if my memory is failing on the amount so I won't quote it) the gun was his and sure enough, it went home with him. Well, at a later THR shoot he had the same gun with a red dot attached. That red dot sight raised the check weld just enough that the gun didn't punch my face anymore and it was also quite accurate and added to the fun factor. Now, I'm thinking that at the prices these things sell for I just might have to pick up another along with a cheap red dot sight.
Anyway, that is my sad history of gun sales and trades. Even those I don't regret, I sometimes do. Even those I regret, I usually had a reason for selling so I don't fully regret most. The only two I truly regret selling are the CZ 40B and the Taurus 82 since my reasons were stupid (though I possibly wouldn't have met THRer Spot77 if I didn't sell that CZ so it may have been worthwhile from that perspective), though I may reverse others even though my reasons at the time were sound.