Barry Halper single-signed baseball. Famed baseball memorabilia collector Barry Halper signed the sweet spot of this Rawlings Official National League (White) baseball with a blue ballpoint pen. The ball is in excellent condition with some minor spotting and toning, and the signature rates 8.5/10. Halper put together one of the largest collections of baseball memorabilia in the world. The main focus of his collection was the New York Yankees, and he owned items signed and worn by Mickey Mantle, Joe DiMaggio, and others. A PSA sticker is stuck to the back of the ball.