My neighbor has a ball signed by Ruth. The Babe was in Long Beach for some reason, but not playing. We didn't have any major leagues out here on the West Coast then.
The provenance of the ball accounts for variables in value. Since this ball was not even sighed at a ballpark, it's worth less. It's real though, because the neighbor's dad was the one that got the autograph in person.
AFAIK, it's rare to find BB's signed with a message such as, "To..." if at all.
That might be a book thing.