I haven't really thrown anything out, my retro collection is relatively small in comparison to others that I see online, I just don't have that much space and I probably have too much right now anyway.
I did sell my C64C setup (sans monitor) to an online mate of mine (mutual followers on Twitter back when that was used, remember that network?) as he wanted to get back into 8 bit retrocomputing, I wasn't looking to make money off him so I sold it to him at cost. The C64C never really resonated with me as my formative computing experiences were 99% with the Amiga.
Having said that, I have accumulated some other retro computers that I probably need to part ways with. I have a couple of eMates (one is a part machine) that has been sitting around for years doing nothing. The good one works pretty well but needs a battery repack. I did initially invest in an eMate to experiment with distraction-free writing but since becoming a dad this is a very lofty ambition. A Slack channel I'm on had someone who was pining for an eMate, so I should probably hit him up and offer these two eMates for sale to him.
I also have a PowerBook 1400c with a replacement screen to go into (and all the cardboard graphic inserts that go into the lid) but again, MacOS 8 wasn't really my jam when I was younger and so I have no emotional or nostalgic attachment to it. I should probably let that one go too.
My dad also found an IBM PS/2 386SX that was being tossed out, along with the famed Model M keyboard, so I pinched that off him if only for the keyboard, but there's this rest of the PS/2 (it was just the main computer + keyboard, no screen) that I don't know what to do with. My nephew is getting into retro computing at only 11 years old, I might hand it over to him and see what he does with it. The PS/2 still has its hard drive (along with the software that was used at a hospital! thankfully no personal records) but I feel it might be a bit underpowered for my nephew, his idea of retro computing is either 8 bit or 486/Pentium era gaming.
So TLDR, I don't have an extensive collection, but am wary of getting rid of the stuff I do have, lest I do regret it later on.