Put it up for AuctioneBay would be a good place to sell the 1955 Dodgers team signed Baseball. If yo sell the baseball to a memorabilia dealer you will only get about half the market value or less depending on how long the dealer feels it will take to resell. You will get the most value from a collector. Signatures that have not been properly authenticated could sell at half the market value or less, and you might want to take care of that before selling. A private auction house will help you sell it and get it authenticated.