Finally, keep your eye out for vintage computer-related paper items or, as we say in the trade, "ephemera." Some early magazines, like the famous January 1975 Popular Electronics featuring the Altair 8800, can fetch more than $100. And at Christie's now-famous 2005 "Origins of Cyberspace" auction, a 1929 IBM maintenance manual, "Care and Adjustment of Electric Tabulating Machines," sold for $840. Who says you shouldn't keep those old manuals?
Vintage 1970s LED watches
In 1972 the Hamilton Watch Company launched the Pulsar P1, the first ever digital watch, utilizing low-current CMOS technology to show the time in a simple display of red digits. According to the lead engineer on the project, they were inspired by the futuristic digital clock in the 1968 movie, "2001: A Space Odyssey."
These 18k gold units (original retail price: $2,100) are the Holy Grail of vintage LED watch collecting. The 30 or so examples known to exist trade for $5,000 to $10,000, depending on condition, completeness (original box), and documentation. In fact, a circuit board for a 1969 Pulsar Hamilton Prototype recently sold for $12,000 on eBay.
[ Rolex? Movado? They can't hold a candle to a Compu Chron. Check out real-time listings of genuine 1970s LED watches. ]
Also on the high end are early LED calculator watches that included a numeric keypad, like the 1977 Pulsar 3822 or the 1977 Hewlett-Packard HP-01, which can each command several thousand dollars in pristine condition. Expect to pay up to $1,000 for other early LED watches from Pulsar, Bulova, MIDO (Swissonic), Timex, Texas Instruments, HP, Compu Chron, and Omega. Models with green displays are particularly rare and command high prices.
In the midrange ($100 to $400) are popular models like the Pulsar P2, famously worn by Roger Moore in the 1973 Bond movie "Live and Let Die." These are more widely available; pricing depends upon condition. On the very low end, if you just want to recapture the sensation of turning off the lights and pressing the button to see the time shown in red (LEDs drew too much power to leave them always on), there are plenty of other LED watches available for less than $100.
LED watches were ultimately replaced by more efficient always-on LCDs in the mid-1970s, when Texas Instruments introduced a mass-produced model for only $20, soon followed by Seiko, Casio, and others. People collect these too, but it's not the same geek experience.
Vintage slide rules
Though invented in the 1600s by William Oughtred, mechanical slide rules didn't really peak until the 1950s and '60s, just before the birth of the electronic calculator. In the wake of the surprise 1957 Russian Sputnik launch, America spawned a generation of engineers, all carrying this indispensable tool. (To see slide rules in action, just watch the movie "Apollo 13" -- they're ubiquitous.)
[ Long before the computer, the slide rule was the ultimate geek accessory. Check out the wide range; some are genuine antiques. ]
The rarest slide rules are 19th-century hand-engraved instruments such as Palmers Computing Scale (a circular model), first published in 1843, or the cylindrical Thacher's Patent Calculating Instrument slide rules produced by Keuffel and Esser in the 1880s. These can run close to $1,000 and are fragile antiques (taking them down to the track to calculate odds on the next race is not advised).