Baseball bats that are autographed can be of great interest depending on whose bat it is, and if it was used in a game. Bats that are unbroken carry greater interest than broken. Protective sleeves are available to keep the wood from deteriorating over time.
Autographed balls, no matter the sport, vary in price. Balls used in games garner the greatest interest, while balls designed for autographing are a little less in demand. The greatest significance is generated by whose autograph(s) is on the ball. Find a ball protector to keep it in good condition.