If you've spent any time flipping gadgets, you've probably noticed that they're much easier to buy than to sell. One can buy a used iPhone from half-a-dozen places at this point, often with no more than a few clicks — but try to sell one, and you're stuck with either eBay or a hodgepodge of forums and mini-marketplaces.

A new iOS app, launching today, claims to fix that, offering a streamlined path from listing to payment. It's called Sold, and it serves as photographer, broker and banker for each item, finding a price and a seller for you automatically, and collecting its fee from arbitrage. If the system works, all you'll have to do is snap a few pictures and pack a single box — as long as you're willing to let Sold set the price and take a cut.

The business is built on finding the best price on any given day

Notably, this isn't like Gazelle, where you're selling an item directly to the company; you're selling to a private buyer that Sold finds for you (though in both cases, you're going to make less money than if you had sold it yourself). The core of the app is the pricing algorithm, which predicts an optimal price for each item based on your photos and description. eBay punts on this point, letting the auction system determine the final level, but Sold prides itself on telling you upfront how much you'll get. Of course, this makes Sold yet another middleman in the long chain of middlemen involved in selling stuff online — and like any middleman, Sold wants in on the action. You're trading money for convenience.

The project started as a marketplace study at the MIT Media Lab, and in development, the team put a lot of time and computational muscle into clocking the different markets. And with investment help from Google Ventures, Matrix Partners and Greylock Partners, they've had the expertise and resources to make it work.

After settling on a market price — a black-box process that the seller isn't a part of — product defects are picked up by Sold's crowdsourced labor team, run on what co-founder Tony DeVincenzi describes as an in-house version of Amazon's Mechanical Turk. The algorithm knows how much to deduct for each scratch, and along the way, the team has picked up some surprising tips about boosting the sale price. One trick, Tony relays, is that just turning on an iPhone's screen for the photo is enough for a ten-dollar price bump, so Sold will encourage you to do that. The end result is a seller price that Sold knows will get a response within a relatively short period of time.

Just turning on an iPhone's screen for the photo is enough for a ten-dollar price bump

And again, Sold takes its cut from the seller price, so the price you get will be lower than you might get otherwise. How much lower is a bit of a mystery: Sold uses something they call opaque, dynamic pricing, so they won't tell you how much they're getting for a given item. But in return, Sold takes care of writing the listing and emailing buyers, so the next time you hear from them is when you find out the item's been sold. You'll get a pre-labeled, pre-paid box to ship off the item (usually through FedEx), and get an automatic deposit once the item's been received.

The service probably won't be too appealing to eBay veterans, but DeVincenzi is hoping that it will draw in a new crop of sellers scared off by the auction process. Because the process is less automated, it also means it's only worth it to deal with lightly used name-brand goods, so you won't be able to use it to unload anything that's too obscure or too heavily used — but if you notice an influx of last year's Canons hitting the forums in the next few months, Sold might be why.