Back in early 2010 when an Apple I computer sold on eBay for $50,000 it was regarded by the vintage computer fraternity as a gross over-valuation – but by December 2010 another had fetched £110,000 in a Christie’s book sale.
This summer the Apple I made yet another financial advance, selling at $310,000 (£198,960) in a Sotheby's New York book sale.
Produced by the late Steve Jobs and Steve Wozniak in the garage at Jobs' parental home in July, 1976 - a month in which America's bicentennial celebrations were the big news story - the Apple I launched another revolution.
It was sold without any casing, power supply, keyboard or monitor, but because the motherboard was completely pre-assembled, it was in effect the first personal computer and a major advance on their competitors' self-assembly kits - even with only 4KB of memory!
It was however very expensive at $666.66, and when a much more advanced Apple II came along in April of the following year, a precedent was set for that now familiar rule that any new piece of kit you might order needs an update by the time it arrives. But the price had dropped to $475.
Around 200 of these revolutionary machines were assembled, of which around 150 sold, and it is thought that around 50 examples survive.
Of those, half a dozen, including the one seen at Sotheby's New York, are still working.
It came with an Apple cassette interface (supplied at the time at an additional $75), operating manuals for both the Apple I and the interface, plus a Preliminary Apple BASIC Users Manual - not one of them running to more than 12pp - and all those extra bits needed to make it useful.
One week later, on June 22, Christie's New York offered another Apple I, but though similarly valued at $100,000-150,000, it was not quite so complete or attractive a package and failed to sell.