I guess some of the less succesfull 8 bit machines would fall in this category. The OS-market was fully open back then, with every machine having its own OS. Dozens of different computers, most of them were never heard of again, others became icons of the computer industry.
I think the
Enterprise would nicely fit in this category. A (very) powerful 8 bit computer combined with a major commercial failure it is a pretty rare find nowadays.
I still remember seeing one of them in a local computer shop back in the days, it being a rare duck even then. Would love to have one of them now, though.
