Probably not the rarest or most desirable stuff around, but still not stuff I see a whole lot.
10.) XT-IDE 1.0 - I don't know if anyone's still using these anymore. I bought mine sometime around 2010 and it lived in the case my 486 is now as an IBM Industrial PC in clone clothes at that time. Now it runs in my Tandy 1000 with a 3GB Seagate from a NEC Ready 9522 Tower. I'm still running with the firmware I put on it way back when and as of late seeing frequent use with as much as I'm BBSing with my Tandy 1000 these days. It seems most people are using Lo-Tech and newer variants aimed at CF cards. I'm still running nothing but oldschool PATA and occasional adapter'd SATA in my oldschool boxes these days. This was the one the forms sold back when we were called just "Vintage Computer Forums"
9.) A Mac SE FDHD with a still working original 20MB HDD, manuals, 2 original Mac SE mice, and even a Trackball whose brand escapes me at the moment that has a passthrough for the keyboard or to run it inline with a regular Mac mouse (which is what I usually do). I hardly play with this setup though because I want to find a NIC for it but those seem to be worth the Ark of the Covenant on e-bay so I never even bother to offer for them.
8.) A boxed copy of Las Vegas Super Casino for Windows 3.1x on CD-ROM and 3.5. My friend who restores thinkpads gave me this a few years ago. Kind of neato to see this kind of budget software in it's original packaging with original documents all these years later. Actually, probably the more interesting stuff I have that's not common is working boxed software.
7.) A huge lot of Sierra Adventure games in the original boxes I bought for a buck each back in the 2000's. Seems like someone around South Everett dumped off their Tandy 1000 and associated equipment around that time. Within that period, I found Emporers BeQuest, Triple Pack, Kings Quest III and IV in individual boxes, The Black Cauldron, Space Quest I & II in their respective boxes with stuff, and Police Quest I (I have II on the triple pack with Hoyle Card Games and Manhunter II), and a original copy of Manhunter.
6.) A sealed Linksys Ether16 LAN card from the 1990's, ISA. I found 3 of these at the south Everett Goodwill in the late 2000's, I've used 2 (in my 286 and 486 currently). But I kept one in the shrinkwrap. I don't think you'll find ISA cards shrinkwrapped in the original box that much anymore. But hey, I could be wrong. The shrinkwrapped is the "open in case of emergency" one.
5.) I have a boxed copy of OS/2 2.1 with Win OS/2 and Multimedia Extensions that came with 5.25, 3.5, and CD-ROM editions. I still install it periodically but I' have never really fully explored it. I picked it up waaaaaay back in the early days of Creeping Net circa 2001-2002ish. Most of the time I tend to isntall it on VMs on my Linux box to play around every once in awhile. Still has all the manuals as well, though missing the 3.5" install media.
4.) NEC Multisync II JC-1402HWA 14" CRT - I've been blessed by having TWO NEC Multisync 9-pin monitors in my time, but this one is my favorite. I saved it from a pitiful fate in a scrap pile at Computer Surplus in Redmond in 2017 and all I had to do was bodge-wire the input board back together and it's been a real workhorse on my vintage PC's ever since. It's the first monitor I ever actually tore down and fixed, and it's been rock solid. What's really cool is it works with my VGA systems, as well as the CGA Tandy 1000, and EGA systems I might run across if I'm lucky (kind of wish I had my Deskpro 386 again).
3.) The XT Case on my 486. I bought it from bjsurplus in 2004 on e-bay, and that's the only place I've ever seen one other than davejustdave's youtube channel - which I suppose he bought the same case from the same place I did as it seems they had that thing on E-bay for almost a decade at least. It's kind of an odd design that is made to be able to offer 4x half height or 2x full height slots like an XT, or the covers can mimic a "Mini-AT" look by leaving the middle two external drive bay covers in place for a hard drive(s). Of course, I use all four since I soup the heck out of my systems.
2.) The AT Case on my GEM 286, which I believe is Songcheer brand like my XT, but more deluxe. It has an odd chocolate milk-ish hue rather than beige. I've not seen another one like it until E-bay this year, which is about 15 years since I bought the 286 in 2005. It also interestingly is powder coated on the inside the same color and texture as the back cover, and the front plastic is molded in white but painted gray from the factory. Bland subject, yeah, but most AT clone cases I've found are either trying to copy IBM by being black in back or having a plastic bezel in really rare cases like the AT originally had, while most are plain bare steel. GEM Always had weird cases on their stuff, my favorite is still the full AT clone of a Compaq Deskpro 8086 case my GEM 386 had years ago.
1.) Tandy Deluxe Mouse - I have this on my Tandy 1000A, I just got it, and I've been looking for it for a little over 10 years so far off/on. I was admittedly a little scared off from it by the TV Dog Tandy 1000 FAQ due to it's limited movement but I actually find it to be quite a nice and useful addition, though it does indeed handle differently than a regular mouse. Hoyale Card Games for DOS has gone from being a "Why the heck do I have this" game to one of my favorite DOS card game collections, esp with the proper Tandy 1000 sound.
Whats funny is the most valueable stuff to me are my ratty or well used stuff like my frankenstein 486 XT box with Case in #3, the NEC, and my original VGA release of Monkey Island in beat to hell box with a bolted-together Dial-A-Pirate wheel that is STILL - after 30 years - a staple on EVERY Creeping Network PC I deploy on my home LAN.
what models do you have ?