Jeremiah Johnson was flying his battery-powered drone above a park in Brooklyn on a recent weekend when he saw something in the distance.

Faster than you could say “speeding quadcopter,” Mr. Johnson, a design technologist, realized it was a small, remote-controlled aircraft just like his — and it was only about 150 feet away. “We were eyeing each other,” he said, “sizing each other up.”

Not long ago, drones were a relatively rare sight over New York City, usually piloted by photographers. But now drones are soaring as never before, deployed more and more by those who just love gadgets, as new models come on the market at lower and lower prices.

But their proliferation has also resulted in problems.

Two men were charged with reckless endangerment in July after the police said a drone they were flying in Upper Manhattan came within 800 feet of a New York Police Department helicopter near the George Washington Bridge.