Since I picked up some Tallys, I'm mostly good.
I sometimes regret selling the Korina Standard. I was blaming a guitar for a player issue. I regret trading a seafoam green PRS DGT for largely the same reaason and a smidge of wanting to own a Cali. Turns out, I prefer other brands for super strats and got rid of the only PRS I ever really liked to find that out. Pretty unlikely that I'll drop $2k plus to have another one. I do miss the pagan gold SoCal Charvel I had from that first batch of USA production models they did back in 2008. That was a cool guitar that I bought for nothing in 2012 or 2013 before super strats with Floyds got hot again.
That's really about it. There's a couple of other things that were cool to have just to have that I will probably never have again, but I never find myself heading to a gig and thinking, "Man, I wish I had that to play tonight!"
The only guitar-related kit I ever sold that I really regret is a Mesa Mark III I had. I'd had the R2 mod done and had it recapped and everything. It was an absolute beast of an amp and did everything I hoped a Mark IV and V would do but never seemed to. I think I may have had $1000 in that amp, including shipping back and forth to Petaluma and paying for the mod.
But here I am talking amps in a guitar thread.