Prices for Everything: Priceonomics

The website Priceonomics claims to be "the price guide for everything."  

"We search and analyze hundreds of millions of listings on the web to build our price guides. We hope you can use these reports to get the most value for the best price. Today, we provide price estimates for used bicycles, televisions, speakers, monitors, turntables, computers, cell phones and much more. Some day soon, we’ll cover just about anything you might want to buy or sell. We’re just getting started."

HT: Fred Dent