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 a 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!