Custom products often take creators a long time to make. When purchasing a custom product, you're paying that creator for their time, skill, and materials. Mass-produced cards are generally cheaper because the materials to make them are generally of lower quality and purchased wholesale. Plus, the artists who make mass-produced cards are paid by the company rather than by you. Their work creates many cards that are often not unique or rare. On the other hand, custom creators are making one-of-a-kind products tailored to your needs. The more work and time needed for your product, the more it will cost. But, in the end, you will have something that no one else can lay claim to.