Though companies such as Gazelle have seen sharp increases in site traffic—uSell averages about 750,000 unique site visits per month and Gazelle just passed its one millionth gadget sold—executives still see room for the business of second-hand cell phones to grow as much as 10 percent over the next few years.
"The market is more mature after two generations of iPhones," Ganot says. "People are ready for something new."
But simply raising awareness about the availability of these services and increasing the supply of second-hand devices ready to go to market isn't the only growth the industry sees on its horizon. Along with the demand for used cell phones, the market for electronics such as laptops, MP3 players, and cameras is heating up as well.
"The basic challenge we face is inertia in terms of consumer behavior," Ganot says. "We're doing a lot to get the word out to say, 'Hey, you're buying a new phone—what are you doing with the old one?'"
Meg Handley is a reporter for U.S. News & World Report. You can reach her at email@example.com and follow her on Twitter at @mmhandley.