Sotheby's just auctioned off a working Apple I computer for $374,000. It included the manuals and the Apple I cassette interface. Someone else paid $27,500 for a 1974 memo by Steve Jobs about how to improve Atari's World Cup arcade game.
"Apple 1 computer and Steve Jobs Atari memo sold at auction" (BBC News)
Lot 57: Apple I Computer (Sotheby's)
Lot 56: "Instructions for Converting World Cup PC Board" (Sotheby's)