At the back of Costco's stores, past the televisions, jewelry, jumbo-sized ketchup jugs and tubs of mixed nuts, is one of the retailer's most prized items: The rotisserie chicken that costs just $4.99. Cheap Kirkland Signature rotisserie chickens aren't only a quick way for families to get dinner on the table. For Costco, the chickens are a lure, pulling customers into stores and getting them to browse the aisles, adding sometimes hundreds of dollars worth of items to their shopping carts before they pick up that bird. The chickens have become almost a cult item. 91 million were sold last...