By that I mean kit that has had its 15 Minutes of fame/hype, then the long dark night swallowed it and the manufacturer, never to be seen again, making the piece pretty rare. I don't mean the high-end silly stuff, with the naming conventions only the deranged could say with a straight face (..yes, the two Mega G-Spot Explorers will really make a statement on the end of my Ragnarok Berserker cables and the Krull Chernobyl Mk2 monoblocks, with the reference B-52G Stealth Sidewinder front end)
My example of this category is Siemel, a French military equipment manufacturer who seemed to produce a few amps more or less as a vanity project, never to be seen again. I have the TU10 valve pre-amp which is IMHO really rather good and the rather more polite solid-state TA20 power amp. They sit quietly in my second system, making music, blissfully unaware that their kind is extinct. Pity, really, the TU10 deserved to be better known for longer. Any other undeserving dodos out there?