Below are several sites that can be used to lookup card values and also inventory your collection.Card Prices including Slabs and SIngles
Collectors use Card Hedge to check recent prices, research new cards, and find the best buying and selling opportunities across the sports card and trading card market. Easily track the latest values on all of your cards, search millions of sales, and find undervalued cards. While I use this site as a tool I have included an affiliate link to help support my hobby.
Your source of Baseball, Basketball, Football, Soccer, Racing, UFC, Hockey and AFL Checklists, Set Info, Redemption’s and Analysis
Alt has been around for sometime. They did a branding refresh sometime ago and the site is growing at a face pace. It focuses on Slabbed Cards primarily and can give you an average price based on recent sales that it collects it’s data against. A great tool to have!
Obviously eBay is a primary tool to use when referencing recently sold cards. One thing to note, there’s a lot of fluctuation when it comes to using eBay for pricing. Prices vary depending on time the auctions end and how the item was listed for max visibility. I’ve seen $1k cards go for $10 due to these factors. This hurts the card market. Remember when you buy low on big sites that are used for reference, that very price is reflected in the same card that you’ve purcahsed at some point.