Graphic prints/designs for sticker printing

We require 15 graphic design prints. The images shall be flexible enough to be able to apply different colors to different sections of the print. I want to be able to change the color combinations myself in Photoshop CS3. The images will be printed on Vinyl stickers. I will be handing the files to a digital printing service. Whilst the designs are too be originals - I will offer a full brief and in most case's an image showing the overall effect to be achieved in each case. There will be 2-4 colours and very simple (as they are printed on to a small surface area). Attached is a typical example of what may be required. The hirer shall own all the rights to the illustrations once purchased. The freelancer cannot sell these illustrations. The images must be produced by the freelancer. The freelancer must not use images that can be a copyright violation. All illustrations and designs shall be unique and exclusive to the hirer.