Each independent artist sets the price margin of the printed products they sell. That's why the price of the same product type can vary on different designs. Added to that are taxes and the cost of shipping. Head over here to get more information about pricing on Redbubble.
Since artists control the price margin of their products and receive the profits from their sales, each purchase you make helps support them and their creative work.
Thrifty customers can save a few bucks by: