You can determine the worth of rare football cards by checking the value on a card price guide, such as those available on sites such as Beckett.com, FootballCardsPriceGuide.com, TuffStuff.com or PSACard.com, as of 2015. Another method involves using eBay.com to check current sale prices or locate a seller for appraisal.
The football card price guides on Beckett.com are only available with a paid subscription. FootballCardsPriceGuide.com allows you to find cards according to the year, with the first step being to choose a decade. From here, choose either a specific year or a type of card, such as the Action Packed All-Madden series or the Pro Set Collect-A-Books. PSACard.com also requires you to choose a year in order to view the prices of a specific card.
To find out the worth of a football card using eBay.com, search the site for the name of the player in the card and its year of publication. This displays all active listings on the site for that card, which gives you an idea of its current sale price. You can also search completed listings to find actual sale prices or contact a seller on the site to inquire about potential appraisal services, though not all sellers offer appraisals.