The name Piatigorsky has appeared on this blog many times, most notably for the 1966 Piatigorsky Cup (September 2016), but this is its first appearance for Top eBay Chess Items by Price. The item pictured below was titled '2nd Piatigorsky Cup program - signed by all the players, including Bobby Fischer', and sold for US $999.99, Buy-It-Now. Assuming it's legitimate, someone got a great bargain.
The description said,
This is the program book from the 2nd Piatigorsky Cup Grandmaster Chess Tournament held in 1966 at the Miramar Hotel in Santa Monica. It is signed by all the players including World Champion GM Tigran Petrosian and future World Champions GM Robert Fischer and GM Boris Spassky. As you can see, several pages have small stains; but on the whole the program is in very good condition. The tournament is the strongest one ever held in California. (From the estate of Jacqueline Piatigorsky.)
Condidering the phrase 'From the estate of Jacqueline Piatigorsky', and adding the seller's background...
Interests: Anything concerned with California chess - magazines, photos, letters, pinbacks, tournament bulletins, newspaper columns and articles, posters, tournament flyers and other ephemera.
...it's certainly legitimate.