The most valuable baseball cards are vintage cards from the early 20th century, before widespread production. The oldest card that could fetch big money is an 1909-11 T206 Honus Wagner card. Only around 50-200 genuine Wagner cards are known to exist today in varying conditions. Just a few years ago, a near-mint condition Wagner card sold at auction for $3.12 million, setting records.

Other pre-World War 2 cards that can be extremely valuable include:

T205 White Border set (1913-1915) – Especially high value cards include Eddie Plank, Joe Jackson, and Christy Mathewson. Graded gem mint 10 examples of some could sell for over $100,000.

1915 Cracker Jack cards – Perhaps the rarest set ever produced, with only a handful known to exist for each card image. Even poorly graded examples can sell for six figures. Babe Ruth as a Boston Red Sox is especially coveted.

1933 Goudey Baseball Cards – This vintage set featured some of the games biggest stars of the era. Mickey Cochrane and Jimmie Foxx are two cards that have sold for well over $100,000 in top condition.

Moving into the post-World War 2 era, the iconic 1952 Topps set launched the modern baseball card collecting craze. High-value cards from that set and others include:

Mickey Mantle rookie card (1952 Topps) – Always in high demand from collectors. A pristine Mantle rookie in a Gem Mint 10 grade sold at auction in 2021 for $5.2 million, setting a new record. Even considerably lower grade examples sell for five or six figures.

Hank Aaron rookie card (1954 Topps) – One of the last true “rookie cards” issued before players began signing exclusive contracts with manufacturers that prevented rookie appearances in multiple sets. In top condition it consistently sells in the $100,000+ range.

Roberto Clemente (1955 Bowman) – His only true solo rookie card, as he appeared in a multi-player rookie card in 1954. In Gem Mint 10 condition with the rare “red dot” misprint, a specimen sold for nearly $400,000 at auction.

Nolan Ryan (1966 Topps) – His first “solo” rookie card wasn’t issued until three years after his true 1964 debut. Still one of the most iconic and valuable from the 1960s, with high-grade versions reaching six figures.

Sandy Koufax (1956 Topps) – Captures a baseball immortal in one of his earliest seasons. Incredibly scarce in pristine condition due to poor centering and print issues on many copies from this set. Mint specimens surpass $150,000.

The late 1960s and 1970s introduced many stars who are now synonymous with the modern game. Their high-value rookie cards include:

Reggie Jackson (1967 Topps) – One of the most recognizable names and faces in the sport’s history. Near-mint to mint copies sell for $50,000-150,000.

Carlton Fisk (1969 Topps) – His iconic home run in the 1975 World Series sealed his fame, making his RC highly sought. Near-mint grades typically sell for $30-50k.

George Brett (1973 Topps) – Future Hall of Fame third baseman who embodied Kansas City Royals baseball in the 1970s-80s. Near-mint examples trade hands in the $20-40k range.

-Cal Ripken Jr. (1981 Topps) – His historic record-setting streak endeared him to fans of a generation. High-grade copies command $15-30k due to relatively low production numbers versus popularity.

-Ken Griffey Jr. (1989 Upper Deck) – Widely regarded as one of the most attractive and iconic cards ever made. Near-mint grades command $10-15k and up despite larger print runs versus vintage cards.

This overview barely scratches the surface of the valuable baseball card market. Other factors like autographed or game-used memorabilia cards, rookie short prints, and unusual variations like statistical updates or season-in-review issues can significantly raise values. Condition and scarcity are key components in determining value for vintage and modern popular player rookie cards alike. With many early 20th century cards existing in single digits or handfuls today, their values will likely continue escalating over time.