"I sold it for $160 on Gazelle," he said. "It nearly paid for the iPhone 5, and the whole online process took five minutes."
Gadget sellers like Mathre have a growing number of options to unload smartphones, MP3 players, laptops and tablets. Sellers are going beyond eBay to nearly a dozen online sites such as Gazelle.com that specialize in buying electronic castoffs. Other consumers are selling locally to pawnshops and, most recently, automated kiosks in malls.
While cellphones and MP3 players have had a modest resale market for more than a decade, the smartphone is what's creating a sudden surge of interest, said Dan Brauser, president of uSell, the Kayak.com of consumer electronics resellers.
More than 70 percent of Americans are expected to own a smartphone this year, according to a Nielsen survey. "The higher penetration and the much higher value is what's driving the resale market," Brauser said.
Not only are more Americans connecting to smartphones, they're switching to a new device every 18 months instead of two years.
Online buyers such as Gazelle, BuyBackWorld, NextWorth and BuyMyTronics are attracting the bulk of attention. They provide quick online estimates after a buyer completes a few questions about model and condition. If the buyer wants to sell, most companies send a box with prepaid postage for mailing the item.
But options such as Pawn America also are seeing an influx of sellers.
Where to sell your old gadgets
Here's a sampling of options to get cash or credit for older models of cellphones, tablets, laptops and MP3 players.
Sites: BestBuy.com (store credit), BuyBackWorld.com, Gazelle.com, NextWorth.com and Target.com (store credit). USell.com is an aggregator similar to Kayak that lists bids from multiple resellers.
Kiosks: EcoATMs can be located online at http://www.ecoatm.com.
Brick and mortar: Pawn America and other pawnshops,
How much for an iPhone 4s?
A survey of prices for a 16 GB iPhone 4S in good to excellent condition produced a range of results. All offered cash or check, except as noted.
Bestbuy.com: $280 (store credit, not cash)
EcoATM: $140 to $175 (based on recent sales)
Pawn America (Bloomington, Minn.): $150 to $180
Target.com: $170 (store credit, not cash)
USell.com: $70 to $210 (multiple bids offered)