The main game is price matched at most other retailers while the DLC is around $5. If you'll scroll down, on the right you'll see the "to play this game you also need" link.
Shop bestsellers, action & adventure, and more. You will find savings of over 5,000 titles including We are the Dwarves for 74 cents, it's a low by a buck. Some titles are some of their highest ever GOG discounts.