Well the ball is obviously a team issued 1963 Cubs ball. Banks and Williams are both Hall of Famers along with Lou Brock who was the CF for the team. It is really hard to value the ball without seeing the ball in person or through great photos. Just to make sure it is not a stamped ball, and to verify the other 23 signatures. If you would like to take some great photos i can ask around[i work in the autograph business, i run
http://www.americaniconautographs.com] and see what it is worth. In my opinon though, i would say near 250-400 dollars depending on how great the signatures are and what location on the ball, etc etc.. There are a lot of things to consider. As per the previous entry, the only reason that the 88 and 89 Oakland ball is going for anything is because of Big Mac. With three certian HOF's you might have come across something real special. Anyways let me know. You can reach me at webmaster[@]americaniconautographs.com Just take out the []....
PS here is a site for the entire '63 team..
http://www.baseball-reference.com/teams/CHC/1963.shtml
Also if you have proof of where your husband got the ball, or anything else for that matter it will help in the selling. Also i am very sorry to hear about the loss of your husband.