Because you are asking the value of a Signed "Broken bat" I'm going to take it that you have a "game used" bat, used and signed by Kelly Gruber. A broken store model bat to display a signature will have very little value. The bulk of the value will rely on The provenance or authenticity accompanying the "Game Used Bat.
With out any letters of authenticity as a game used bat, with the proper bat markings as a pro bat it will only sell as such. A Kelly Gruber "broken" pro model bat. As only a pro model bat it will still have a low collectors value because it is broken. A Kelly Gruber Signed "Broken" Game used bat would probably sell for about $75. -$125.,and less without a COA for both the Game used bat and signature.
Keep in mind that most "Game used" collectors would rather have the item unsigned, and autograph collectors are looking for a displayable signature
$1200.00
In the low 1,000s
On Amazon, Vin Scully autographed baseballs can go for as much as $295.80
About $1,000 to $3,000
Close to $300
$50
$800,000,000
Anywhere from $20 to $40.
The autographed baseballs are valued at a price between $40 and $60. The exact price will depend upon the condition of the baseball and when it was signed.
I would estimate $25.00 - $50.00
$0 to negative. It may actually lower the price of the baseball.
Autographed baseball cardsIn general, collectors of baseball cards would rather have a baseball card without the signature. The signature would be considered as a flaw in the condition of the card and will lower the value. If the signature has a lower value than the card it will lower the value of the card. The un-signed card will have a higher value.