Old Microphones (as high as $9,999)

Colloquially called a mic or mike, a microphone is an apparatus that converts sound into an electrical signal and is used in several applications, such as hearing aids, telephones, sound recording, speech recognition, and many more. The first microphone was invented by Alexander Graham Bell in 1876 and was used as a telephone transmitter. It was Thomas Alva Edison, however, who invented the first practical carbon microphone in 1886.

More than a century later, it has become even more useful and lucrative, and more and more people are on the prowl for their next prized item. A Neumann U-47 from the 1940s can be worth tens of thousands of dollars online. As a matter of fact, one was sold on eBay for $9,999 — it was a good investment for the owner.