Manhattan's luxury apartment market is feeling the squeeze, with some prices down 20%.

Attention bargain shoppers: The late Brooke Astor's duplex at 778 Park Ave., with 14 rooms, six terraces and a brass-trimmed library with red lacquer walls, would have cost more than $40 million just three years ago. But today, less than a year after the listing debuted, the trophy property has a new broker and a new price tag: $29 million--a 37% discount.

All across Manhattan, but mostly concentrated in the Upper East Side, owners of luxury residencies are cutting prices by 20% to 25% on average, according to Stribling Executive Vice President Kirk Henckels, the broker of Astor's estate.