Daniel Nissanoff

HOW WILL WE SHOP IN THE FUTURE? Historically, we have bought things with the expectation that we're going to own them until they break or we give them away. We're evolving into a more efficient, temporary-ownership society, in which we buy things with the expectation that at some point, we'll trade up, similar to how we own cars.

EBAY'S 180 MILLION USERS MADE $44 BILLION IN TRANSACTIONS LAST YEAR, BUT ONLY 5% OF THOSE WHO BOUGHT ALSO SOLD. WILL THIS CHANGE? There is $2,200 in unused goods sitting in the average U.S. household, which adds up to about half a trillion dollars nationwide. That's where the opportunity is. Over the last two years, more than 7,000 "drop shops" have opened around the country. These are storefronts that don't sell anything except services that help you sell your stuff. There are "personal reselling assistants" to help you get rid of the things you no longer need, and "closet cullers" like clos-ette.com that regularly sell things that are out of style or you're no longer wearing.

WHAT'S BEING BOUGHT AND SOLD? The most popular consumer goods on eBay are designer handbags, shoes and accessories, and high-end crystal, furniture, art and electronics. There are other auction sites too. Amazon has a cooperative marketplace with a store-within-a-store concept, like a Louis Vuitton boutique in Bloomingdale's. Google just launched Base, which brings buyers and sellers together through advertising. Then there are niche players like [my company] portero.com for luxury goods.

HOW MUCH CAN YOU GET FOR TWICE-WORN $800 JIMMY CHOOS? It depends on style, size, color. In the most favorable scenario, if it's a hot model that's not readily available, you'll be able to sell it for what you paid or more. On average, if you're savvy and they only have a few scuffs on the bottom, you can get as much as 80% of the original value and use the proceeds to buy your next round of clothing.

WHAT ABOUT FRAUD? Kate Spade has hired 13 law-school students to sit in front of a computer all day scouring for fakes. When they find one, they shut down the auction with the push of a button. Also, drop shops add a layer of accountability because now there's a real business you can look to if what you get is not what you ordered. You're no longer dealing with a stranger on the other end.

HOW WILL AUCTION CULTURE AFFECT THE LUXURY INDUSTRY? People are going to reach because they recognize that buying better brands is going to be a better value. For example, if you buy a new Bugaboo stroller for $750 and use it for two years, you can resell it on eBay for $550, and your net costs will be less than if you had bought a new $250 stroller and thrown it away. And your child will be much happier. The brands that are going to be hurt by this culture are those in the middle because they won't retain significant value in the online market.

HOW WILL WE SHOP OFF-LINE? You'll start thinking, Do I want to buy a classic handbag or an "It" bag in a trendy color? There's not a big difference in cost, but the classic bag has residual value. Also, you're going to shop more frequently because you're going to be able to move in and out of goods for the same price. At least one large department-store chain is considering reselling customers' clothes on eBay in exchange for store credit. Imagine buying a new handbag that comes with a card that says, "When you're ready to sell this, call this number, and someone will pick it up, sell it and give you credit toward your next handbag."

WHAT HAPPENED TO THE STIGMA ABOUT SECONDHAND GOODS? The Internet allows you to be anonymous in your purchasing. It's not like you're rummaging through someone's garage. When you walk out of your home in that designer dress, no one will know it was previously owned. Also, some things are being sold on eBay with the tags on.

DO YOU FUTURE SHOP? I regularly buy and sell watches online because I enjoy nice watches, but I also enjoy variety. When my wife has a loud, uniquely colored cocktail dress and doesn't feel like spending a few hundred dollars on a pair of shoes she'll wear with it once a year, she'll buy a gingerly used pair on eBay. I get a new computer and cell phone every six months to a year.

YOUR BOOK IS ON EBAY FOR $5. I know I need to live by what I preach, but I sign as many books as possible so people have incentive to keep them.