1. Charter Arms .357 Mag Pug
I knew this would be a low quality gun, I bought it on the fly to use as a carry piece until my desired carry piece showed up. $300. After about round 100 the cylinder would lock up when firing DA, almost to the point where you would have to turn the cylinder with your hand to help it out.
So, I sent it to Charter Arms for repair. $100 later, they did fix it. But it wasn't worth the shipping. I sold it to a buddy for $250, who then offloaded it at a gun show for $200.
2. Ithaca M37 "Police" Shotgun
Bought this as an impulse buy from a police auction. $240. [Edit=fixed this: 7+1] shot, one of those "slam-fire" prison specials. Real good condition. I found out why. Any and everything I shot through it would stick in the chamber. I tried polishing the bore, replacing the extractors, that gun would not fire reliably. Some gun show vendor owns it now.
3. Sig Sauer P250
Bought this for $700 brand new. I was looking for a .45 that had a hammer and had more than 7 rounds. That DAO trigger was about 18lbs, and the handgun consistently shot low and to the left. It got off loaded for $400 (yeah, I got stiffed) which I used to buy a P-3AT and some other stuff.
Oh, and after this, then I found out about the FNP-45. Best .45 I've ever owned. Love that pistol.