Do you have a T-shirt signed by David Beckham or Muhammed Ali's gloves? Our experts specialize in the most popular categories of sports memorabilia including football, basketball, American football, boxing, tennis and golf. When valuing your item, the following will be taken into account: the importance of the event, the issue number, the popularity of the person who gave the autograph and the importance of the item in the history of the game or sport.