Those figurines also take up space. Space they can't use to demo new products or sell anything else. They can't keep the figures in back; as they are an impulse buy, especially used. If someone is looking for a figure at the best price or is a collector, they'll go online.

If the figures don't sell quickly enough, they are eventually going to have to be written off and discarded.

When Gamestop marks up the pricing, it's because they have to account for making a relevant profit on the product when accounting for their costs, including lost profits.

Now remember this is a worldwide business. You as an individual didn't feel it was worth the gains to sell these individually yourself. That tells me you don't believe you could get the $7 per figure; or don't feel that $7 is worth the space they take up in your home. Gamestop has to look an their inventory the same way you look at your home. But where you could decide the figures aren't worth your time and bulk them to someone like Gamestop, they have to just write those same items off.

There's also a massive difference between the markup on a 3 cent item and a 200 dollar one. Go to a pawn shop, and assuming you can sell them TCG cards, you'll get maybe half a cent per. Those same things will be sold for 50cent to a dollar; a 100x markup.