First, IMO the autograph is 100% legit. I purchased a similar Wright from this seller last month for mid-three figures on a signed Proxy slip, Now I am starting to think I overpaid, but I am not complaining.
I chatted with the Seller as he put his initial find on Ebay back in April and has since went back to the original supplier and was able to acquire some additional signatures last month and is slowing selling those off. He said he has a "few more" left, but he would not quantify.
There is another thread regarding the initial listings here:
http://www.net54baseball.com/showthread.php?t=166263