Andy Trench made $2,000 a day in 2015 taking sky-high photographs along the East Coast with a drone he made himself. Now, that same work fetches about $175. "It's apparent that a lot of this industry is a race to the bottom," said Trench, a Rhode Island entrepreneur who's been operating remote-controlled aircraft for more than a decade. Three years after federal regulators began allowing commercial drone flights, the fever to cash in has turned into a pitched battle for business. Prices for collecting airborne data have plummeted amid a flood of competition equipped with cheap, hi-tech aircraft that practically fly themselves.