Her 32-year marriage to research biologist Leon Weiss has been her first and only—and his. But Ellen Weiss usually falls for secondhand goods. For much of the past three decades, says the Merion, Pa. housewife, people looked down their noses at used merchandise, so she kept her shopping secrets to herself. Then Barbra Streisand went on the Tonight show in the late 1960s and announced that she bought her clothes at a thrift shop. "I thought, 'My God, she's blown it for the rest of us,' " Weiss recalls. Indeed, bargain hunting became bigger than ever, and Weiss, 52, has just published Secondhand Super Shopper (Evans, $7.95), a guide for the aspiring scrounger.

The book describes where to look for what ("Flea markets for pottery, china, vintage clothes and kitsch, thrift shops for children's clothes, and garage sales for everything from household items to heavy furniture"), how to dress and behave ("When anticipating a snooty setup, affect a tweedy society look; for thrift shopping, forget the gold chains and furs"), and how to beat the competition ("Try not to call attention to what interests you, especially before a sale, and don't count on tips from friends—no one gives away information to competitors").

For those who only wish to dabble, a relaxed approach is fine. But for serious buyers, Weiss recommends a system. Using local newspapers and telephone directories, shoppers should draw up a list of all possible sources—carpet cleaners and moving firms, for example, often sell unclaimed items—and then mark their locations on a map. Enter the dates of upcoming fairs and auctions on a calendar. Thanks to Weiss' bargain network, she was able to furnish her family's Cape Cod summer home with purchases including a stove, a refrigerator, beds and bureaus—all for only $600. She then financed an addition to the house with proceeds from the sale of scrimshaw she had collected over the years.

The New Jersey-born daughter of two lawyers, Ellen made her first secondhand purchase when she was 12—a Victorian petticoat for 25¢. Her mother did most of the buying back then, but Ellen had developed an appraising eye long before she graduated Phi Beta Kappa from Barnard in 1950. That same year she married Leon, now chairman of the Department of Animal Biology at the University of Pennsylvania's School of Veterinary Medicine. His first response to Ellen's unusual shopping jaunts, she reports, was to fall asleep in the car. "But he was generally supportive," she adds. With good reason. Ellen's secondhand buys helped keep clothing bills to a minimum for the Weisses' three girls and three boys, now ranging in age from 13 to 27.

Through the years Ellen has uncovered her share of treasures: a 10¢ wallet with two $50 bills hidden inside, a $1 strand of beads that turned out to be lapis lazuli now worth $1,000, and a 1930 Burberry coat that she bought for $3 and that the Metropolitan Museum of Art wants for its costume collection. "But I never buy hoping to make it big," she insists. "I buy what we need and what gives us pleasure. Enjoy yourself," she advises. "Then you've always got a return on your money."