Oh man, where do I begin?
I've traded into and sold at least 8 Ruger 10-22s and never looked back.
I bought, tried, and ditched a Taurus 92 clone in 40 S&W. Me or that pistol couldn't shoot straight.
I bought 20 35.00 Turkish Mausers during the glut 10 years ago or so, cleaned them up, made sure they were safe, and gave them away as Christmas gifts. I didn't regret that for a second. I liked the Mausers, but how often do you get to buy everyone in your family a gun for Christmas?
I bought and dumped an Iver Johnson Enforcer carbine in .30 Carb. What a junker that one was!
I've traded into and out of several recent-vintage Savage Bolt actions. I never regret it, because I turn a little profit and there's no shortage of those things in this neck of the woods.
I recently sold a Wichester 94 and Mossberg 590 to fund my purchase of a .45 longslide and a .22 Mag Revolver. I don't miss them yet.
That's just off the top of my head.
KR