Acts as a middleman. You ship them your cards, and they find the best buy-list prices across multiple vendors for a small fee. Marketplaces: For Maximum Profit
Bulk collections, common cards, and people who don’t want to deal with shipping or online fees. places that buy magic the gathering cards
Offers a "Ship + Sell" program where you can send an unsorted collection and they will grade and price it for you. Acts as a middleman