Oprah’s book club selections have resulted in the sale of 30 million books. Her 2007 endorsement of Barack Obama is said to have created 1 million votes for the candidate. But she’s a style icon as well: The deep-purple dress Oprah wears on this week’s big Surprise, Oprah! A Farewell Spectacular will soon be available in stores. Designer L’Wren Scott, who custom-made the dress for the TV queen, has created a less-expensive version, which will retail at Barneys New York beginning next week.