Answer

For historical coop unit sales, visit the Jack Brause Library and take a look at the archive of Redbook, covering reported sales of coop, condo, residential building, and single family properties in the New York City area, published by Market Data Center (CoreLogic from 2006-2012). For more recent coop unit sales, access to PropertyShark is available to currently enrolled NYU students onsite at the Jack Brause Library, NYU Midtown Center, 11 W. 42nd St., Suite 510