A bicycle wheel with guitar strings, a touch-operated synth, and the “Demon Box” were just a few of the new instruments on show at Georgia Tech’s Guthman Musical Instrument Competition this weekend.

Buying used gear is a stressful and exciting event no matter where it happens. Whether it's a conversation on the ever-more-popular Facebook Marketplace or its web 2.0 equivalent, Craigslist, a flyer ...

All of these instruments were made by Antonio Stradivari, and are valued above $15 million.