As some of you've already noticed, the page has no game price or "Add to Cart" button, even though the game was released yesterday.
I don't know why this is happening. I've tried looking everywhere on my configuration options, and haven't any clue as to what is causing the problem. I contacted the Steam Support yesterday right after I noticed that something wasn't right, but until now I got no response from them.
About the price, the game was released costing $8,99 USD with a 10% discount ($8.09 USD).
As the game can't be bought right now, one option is to add the game to your Wishlist, so you can keep connected to the game in some way. Another option is to Follow the game because I will post an Announcement here as soon as it is possible to buy the game.
Thank you for your understanding.