Call it the dress that launched a thousand knockoffs. The $620 Issa London sapphire dress that Kate wore to her Nov. 16 engagement photo call sold out online within hours and sent high-street retailers into a production frenzy. Just one week later, the supermarket chain Tesco had churned out a $26 cotton imitation featuring the same plunging V-neck and wrap effect. Consumers snapped up the entire stock within one hour, the dress became the store's best-ever-selling frock online, and Tesco relaunched the same style in red and black. On Dec. 2, Cardiff-based retailer Peacocks undercut Tesco with its own polyester-and-elastane replica — the $22 royal blue wrap dress. Announcing the Peacocks version, head of ladieswear Antonella Bettley said the rip-off will make women feel "every inch a princess whether they choose to wear it to a Christmas party, or whilst dropping the kids off to school." Sadly, it won't guarantee them a prince of their own.