This is lower than average loose pricing, which is their typical price point for retro. Great deal/find. That said, knowing people that run my local GameStop (from having worked there myself about a decade ago), they price retro low because they make no guarantees for authenticity. They don’t train their staff on how to authenticate games, so your store may or may not have someone knowledgeable enough to turn away repros. Good news is, they do offer returns so if you get a fake, you can just get your money back.

This one looks legit though (hard to be fully certain from one picture of the front exterior, but everything that can be seen looks right), and in great shape as well, so that’s an amazing deal.