What a sweet project! The book sounds fantastic, and I'd love a chance to make this cover for you. I can create a high-res image, exactly as you've described, that we can easily export for print, web, mobile media and as a giant poster. I usually charge more for big projects like this, but it's such a fun idea that I'd do it in a week for $225. I'll send you some sample work via PM. Let me know what you think!