Lie detector
I used to work at a company doing some complex identity proofing and background investigations. Working with the FBI got me really interested in, well, lying. So when someone told me they were throwing out a 1962 GRASS Model 7 Polygraph, you better believe I moved quick!
It is a beast, probably weighing 200 lbs, so moving it wasn’t easy. But it is beautiful, all stainless steel and aluminum and analog, with massive tube amplifiers and a growling power supply. After a couple months, and some very esoteric parts, I got it running!
But I hit a snag, I needed the sensors that actually attach to your body (or, rather, the body of the liar). The manufacturer has old stock available, for hundreds and hundreds of dollars. So I tried an old trick- I called and asked if there were any retired engineers or support people from Grass Industries that might be available for consulting work, thinking they might have some old parts (and advice). Needless to say, the lie detector company did not fall for my lies.