Another recently discovered vintage computer gem is this Altair 8800, from MITS.
Long known as the machine that jump-started the microcomputer revolution--largely because it made it possible for hobbyists, for the first time, to get their hands on a machine of that kind--the Altair is famous for having inspired Bill Gates and Paul Allen to create a BASIC language at their start-up, Microsoft.
This specific Altair may well be the earliest mint-condition model still in existence. According to its serial number, it was just the 47th assembled Altair. The computers were sold either assembled or as kits.