Whether you need singles, boxes, sets, or even cases, Ebay has it all. I've had great experiences as both a buyer and seller and am proud to be an Ebay Partner. Click the image to the left to start your search or learn more about buying and selling on ebay here.
COMC is a great source of singles from any set you can imagine. Combine purchases from multiple sellers into one low cost shipment. Some images on the site are courtesy of COMC.com.
Sportlots is the place to go to for set builders and player collectors. I've used them for several years to both fill my set needs and sell my doubles. They have both fixed price and auction formats which allows you the flexibility to buy everything from individual commons, stars, or even large lots. They also have a great partner program.
Read more about Sportlots in this review.
Amazon has everything, including cards and supplies.
Beckett is a great place to go for Sportscard information. They also have grading and autograph authentication services. While many collectors use Ebay as a resource to determine card values, Beckett's price guide product can also be used as an alternative source to obtain card values. This is especially helpful for cards that don't often come up for sale.
Topps is the iconic company behind baseball cards as we know them. They produce baseball cards under both the Topps and Bowman brands as well as a variety of non-sports cards. Check out Topps.com for more info about upcoming releases, their retail store, or even to design your own customized Topps card.