In the early days of Print On Demand orders will be performed manually. This means we are limiting how much can be demanded until the software and technology is implemented because it takes man hours to perform the tasks. Making sure this process works across devices takes time and money.
Print On Demand is intended to produce custom deck building at low cost based on the players ordering of cards. You would be able to hand select cards to be printed, and instead of card rarity being a factor of increasing the cost. While Print On Demand is an available option, cards will be the cost of manufacturing and shipping. Cards will be available and unlock-able for example by using your key codes found in booster packs, or by earning them in the mobile app. (It has a time limit, and cards available will rotate)
Print On Demand ends for cards when the limit of printing is met, or a duration of time. After this the cards go to traditional manufacturing. This means rares uncommons etc. This period of time focuses making the demanded and powerful cards the rares for traditional decks and boxes you will find at the store.