His baseball cards, especially his rookie cards, have been invaluable and highly sought after by collectors since the late 1980s. Here’s a list of Ken Griffey Jr.’s most valuable cards.

1994 Upper Deck Mickey Mantle/Ken Griffey, Jr. (DUAL AUTO) / Click image for eBay source listing In 1994 the baseball card scientists at Upper Deck came up with the formula for one of the hottest ...

Ken Griffey Jr. 's 1998 Skybox card sold at Heritage Auction, setting the record for the highest Griffey Jr. card ever sold, ...

Though Ken Griffey Jr.’s ... of Griffey’s best 1990s grails. The 1998 SkyBox E-X 2001 release had two parallel sets: Essential Credentials Now and Future. In the Now set, cards are numbered ...