If you feel foolish for having spent $10,000 for an Apple Lisa-1 computer in 1983, you hopefully kept it.

A working model recently sold for more than $50,000 at auction.

One of Apple’s biggest commercial failures is now one of the most coveted pieces of vintage tech. The steep price, clunky performance, and unreliable Twiggy floppy disks led to poor sales. Apple made improvements and dropped the price on the Lisa-2, but the launch of the Apple MacIntosh pretty much ended Lisa’s life.

An Apple I may not be much use to you these days, but its significance in Apple history makes it one of the most valuable pieces of old technology.

Another rare Apple I, complete with an archive of original documents including the machine’s original user manual, will go to auction in Germany this May — and it’s expected to fetch up to $320,000.