Jem Aswad Senior Music EditorThe $6 plastic crown worn by the Notorious B.I.G. at a photo shoot days before his death was auctioned off for $595,000 on Tuesday at the first-ever Sotheby’s auction focused on hip-hop memorabilia.The crown — which was sold by photographer Barron Claiborne — more than doubled the pre-auction estimate of $200,000 to $300,000.