One of the most important factors that determines the value of a baseball card is the year it was issued. The older the card, generally the more valuable it will be. This is because fewer of the older cards from the early 1900s survived in good condition compared to modern cards. Some of the most valuable sets from the early years include:

1909-11 T206 White Border set – These are considered the most iconic and valuable set ever produced. High graded examples of stars like Ty Cobb or Honus Wagner can sell for over $1 million. Even common players in good condition are worth thousands.

1933 Goudeysubset – This was one of the first modern mass-produced sets. High graded Babe Ruth and Lou Gehrig cards can reach $500,000+.

1952 Topps – As the first post-WWII set, it saw vastly increased production and survived in much higher numbers. But stars like Mickey Mantle are still extremely valuable, with a Mint grade one selling for over $5 million.

1957 Topps – Often considered the most attractive vintage set design. The iconic Mickey Mantle rookie card can reach $2-5 million depending on condition.

Moving into the modern era, the most valuable post-WWII sets aside from the earliest Topps issues include:

1969 Topps – The first year of the “modern” design pattern used by Topps for decades. The Willie Mays and Nolan Ryan rookie cards have sold for over $500,000 when pristine.

1972 Topps – Alex Rodriguez, CC Sabathia, and David Ortiz rookies may be worth over $100,000 graded Mint.

1975 Topps – Two of the biggest modern rookie cards, George Brett and Andy Messersmith, maintain prices over $20,000 when top-graded.

1987 Topps – Perhaps the most iconic modern rookie class with Ken Griffey Jr. A PSA 10 can reach $400,000. Also includes Bret Saberhagen, Mark McGwire.

1989 Upper Deck – The first “premium” brand made a huge splash. A PSA 10 Ken Griffey Jr. rookie brought $298,000 at auction.

While the set and year are most important, the specific player on the card also heavily influences its value. All-time legends like Babe Ruth, Honus Wagner, Mickey Mantle, and Ty Cobb will always command the highest prices regardless of condition or set. Other factors that increase value include:

Hall of Famers and superstar players at the peaks of their careers.

Higher-graded condition such as PSA/BGS 10, which signifies pristine “mint” copies.

Keys to completing the entire set collection, such as rare and star rookies.

Autograph or memorabilia relic parallel cards from newer sets that are more limited.

Numbered parallels like /99, /25, 1/1 that are inserter fewer times per case.

While the prices above represent the cream of the crop condition, there are still hundreds of vintage and modern star cards with values from $50-$1000 depending on player, year, and condition. Hope this detailed overview provides ample context on how factors influence baseball card value! Let me know if any part needs additional clarification.