How much a 1978 signed Ken Griffey card is worth?

Answer 1

A Ken Griffey Sr. autographed Baseball card is worth between $20.-$25. Prices may vary based on condition, and the type of authenticity that accompanies the signature. Signatures that have not been authenticated could sell at half the market value or less.

In 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.