Well, I like the general idea. I briefly checked prices. If one ordered 100 stickers big enough to cover the top of a Mac Mini, the cost per sticker would be roughly 1 USD / less than 1 EUR. Even with additional shipping charges, that is quite affordable

The problem is that the stickers would need to be cut out to fit the exact shape of the Mac Mini (rounded corners). I am not sure how much a custom-made sticker shape might add to the cost.