Three floors are jammed with almost everything you could wish for: track suits, bomber jackets, early 1980s madras shirts, old prom dresses, and fur-trimmed wool ladies' suits with the eau-de-mothball stamp of authenticity. Often, though, Jack's is not so cheap. Subway: L, N, Q, R, W, 4, 5, 6 to 14th St./Union Sq.