The batteries are to maintain memory when the game if off, similar to a regular desktop computer. Because most games used regular AA batteries, they are often replaced or moved off of the boards to prevent damage from leaking. As far as price, there are good references online. PINSIDE will list an average price for each game. I feel that the Boston pinball eBay sales summary is a good reference. Much of it is going to be driven by the collector buying the game. My personal price for that game would be low because its not a game that I would like to own.