The patterned roller is sold by The Painted House and they even provide you with helpful videos to guide you through the process. There are also a small but (let's hope!) growing selection of designs to choose from.
As well as a wall paper applicator they also sell fabric patterned rollers so you can create and even sell your own fabric! Check out The Painted House's ideas page where you can see many of their own creations such as lampshades, wrapping paper, cushions, bunting etc etc... sure to inspire!