Amanda Brooks’ departure from Barneys has also prompted her to donate her designer gear to a thrift sale. Brooks resigned as fashion director of the Madison Avenue emporium in March and plans to leave the city to spend more time with her family at their farm in Oxfordshire, England. Sources tell us Brooks has donated many of her designer wares to the New York City Opera’s annual pop-up thrift shop, opening tonight at 82 Mercer St. We’re told that “thousands and thousands of dollars” worth of Prada, 3.1 Phillip Lim, Jil Sander, Tuleh, Yves Saint Laurent and Chanel designs, plus “loads of shoes,” were donated. Still, it’s not entirely for the people — there’s a VIP preview at $375 a ticket for a head start on the shopping.