The guy has put a lot of effort into the game and he is "fishing" for a fussy buyer looking for a "one of a kind" Whitewater. Believe me, there are collectors willing to spend the money on a unique version of their favorite title. I remember people scoffed at the "pimped" Terminator 2 pinball, and now there's a company in Europe making kits to pimp T2's.
Just because collectors and hobbyists think it is overpriced, you are not buying dealer standards here, you are buying a "one of a kind". The seller is looking to find that one person who will pay the asking price.