Find that perfect sports card and build your inventory over time, or take the leap and buy a pre-owned collection. Whether you’re a casual hobbyist, a seasoned collector, or a serious investor, you’ll find a huge selection of sports cards on eBay.ports Collectors Digest Authentic (SCD). These independent organizations evaluate a card for authenticity and quality. Many use a 10-point grade scale. They then secure the card in a sealed, tamper-evident plastic holder complete with a certification tag, grade designation, and other pertinent card information.