The app is a free download and includes one complimentary sticker set. You can then make in-app purchases of your favourite artist's sticker sets, including custom backgrounds that you're free to mix 'n match any way you see fit.
As an extra bonus, I've designed two brand new, exclusive Sketchbots for Series 1 - Yellow variant w/crayon and Jet Black variant w/rapidograph. I've also broken out the accessories, so you can choose from your favourite drawing tool to include with your wallpaper creations.
I look forward to seeing what you all come up with - be sure to eMail links to your Stikalicious wallpaper images. Have fun!