She's given her Midas touch to dozens of purses since then (Coachtopia's Alter/Ego Hobo, the Saint Laurent Y Tote, and so on), but none so much as Saint Laurent's signature bag, the Sac De Jour.

New Look shoppers are rushing out to buy a head-turning bag that resembles a much pricier version from a designer label. The fashion-forward high street retailer is known for offering trendy ...