
Maggie Bard, 21, an employee at Buffalo Exchange in Williamsburg, Brooklyn, holds up some of her favorite pieces in the store.
Viki Stevenson stands behind the counter, passing fashion judgment. She's wearing a gauzy black Viktor & Rolf blouse and skinny Diesel jeans as she sorts through a pile of clothes in the shop where she works in Brooklyn, N.Y. After rejecting a high-waisted, sequined pink skirt, she snaps up four G-Star narrow-cut cotton T shirts. "You gotta know your brands," she says, as she tosses the keepers into a metal bin.
Stevenson isn't a buyer at an exclusive boutique. She's a store manager who decides what items to accept for resale at a secondhand-clothing shop called Buffalo Exchange. It's part of...