Internet startups sprout all the time promising to send you just about anything via UPS. But one new company has taken the idea a little meta: They'll ship you an empty box.

Sold is the brainchild of three graduates of the MIT Media Lab—Matt Blackshaw, Tony DeVincenzi and David Lakatos—who figured out that boxes aren't as trivial as they seem. One-click buying has become commonplace online, Sold's founders say, but not so one-click selling. And sometimes the difference is a box.

With Sold's app, you take a picture of the thing you want to sell and write a description. The company uses a mix of algorithmic and human judgment to figure out how much you can probably get for the item and sends you the proposed price. If you accept, Sold posts your product on whatever online marketplace the company determine is best—eBay, Amazon or smaller niche sites, depending on what you're selling.

When your item sells, Sold sends you a pre-labeled box to ship it in. (You can track the box while it's on its way to you.) Tape up the box, schedule a UPS pickup and that's it.

"Buying online is really awesome. People have become very accustomed to one-click buying. The confidence is there, and with mobile that's only growing," Blackshaw says.

"The inverse isn't true. Selling online is really awful. It hasn't progressed to the same frictionless transaction that buying has."

As someone who hardly ever sells anything online in part because I never have the right box, I am clearly the target market for Sold. But at least in the company's early stages, there's a hitch. To ensure that stuff sells quickly, and to ease into what at a much larger scale could become a serious exercise in logistical complexity, Sold is pushing hard for early users to sell just a few, mostly upscale kinds of products (see video above): tablets, laptops, cameras, smartphones, designer sunglasses and handbags, headphones and watches. And so far, Sold's boxes only come in three smallish sizes—just large enough to hold any of those things.

Sadly, I don't have any of those nice things sitting around that I'd like to part with. I would describe most of the stuff I want to get rid of under the product category of "crap." It's understandable that the crap market is not where Sold wants to start out. But I'll be interested to see how the Sold concept branches out if the app catches on, and how the company handles the increasing operational intricacy.

I'd call the bigger vision behind Sold "micro-logistics"—the idea that with a little help, our homes can each become tiny distribution centers. The closer the convenience of selling online gets to the convenience of buying online, the more honest commerce becomes. If the artificial scarcity created by the physical barriers of shipping falls away, the whole world of things becomes your inventory. Demand has access to the whole supply. And we all find out what a thing is really worth.