Where should I go to find information on a specific card or set? Lots of sites provide information on cards. TCDB.com provides information on cards and sets, beckett provides card lists as well as recent sales info. Priceguide.cards has pricing info for many card dating back for years.
The best price for a card is what it sold for most recently. A quick search on 130point.com130point.com or eBay sold listings provides the best comparisons for what a card will currently sell for. However, these only really work on cards that sell frequently. For very rare cards or cards that have never sold before the best is to find the best possible comparisons. To find the best comparisons find a comparable player and see if the same card for that player has sold recently. Basically just find the best comparable card and how much it sold for as a general benchmark for what your card may sell for. If this doesn’t work, priceguide.cards offers a service which shows how much the cards sold for years ago and maybe you can find it there.
What contributes to the value of a card? The only thing that influences card values is demand. Demand itself is influenced by several factors:
1) The first and most important factor is who is on the card. The better or more popular the player, the higher value the card.
2) The second most important factor is how rare the card is. Some cards explicitly state how rare they are by indicating their print run (1/10, 1/100, 1/10000). Others are just assumed to be rare based on the frequency they appear on auction sites like eBay. Silvers/Refractors are more rare than base cards.
3) Age of card and the players career. Modern cards of current all stars command a premium and rare cards of Hall of Famers command a premium. Role players from modern eras may have a bit of value and role players from the 80’s are all but forgotten. Rookie cards are generally the most valuable card for a player.
4) There are lots of minor factors such as team, time of year or the eye appeal of the card. However, the player, the age of the card and the rarity of the card are the most important factors.