The price of your packaging is dependent on how many sides you will be printing on. For packaging such as mailer boxes, folding carton boxes, and rigid boxes, we'll typically ask if you want any artwork printed on the outside of the box, inside of the box, or both.
Based on the photos of the rigid boxes above:
Artwork is printed on white paper which is then wrapped over the paperboard. That's why even if you have only 1 solid color (not white) on the outside or inside of the box, there's still printing involved. Learn more about how rigid boxes are made here.