GameStop recently began buying PSA graded cards for cash or in-store credit.
They've added a page on their website that makes it easy to determine how much they will pay for a specific graded card.
gamestop.com/graded-trading-cards/estimate
Once you are at this specific page, enter your PSA graded card's certificate number. It appears as though GameStop puts the card through an algorithm and then displays an estimated value of what they will pay you when you take the card to one of their stores.
This tool has already saved me a ton of time. Before I found out about this tool, I would take my cards to the store and wait for the employee to process my cards. Then they would provide me with a trade in and cash value for each card. This took a lot of time. Now, all I need to do is plug my certificate numbers into this page and I can determine if it's worth going to my local GameStop to sell a specific card.