a) a limited selection so even your totally unique new work computer may end up being one in many (the same happened with Gelaskins for our Android phones, even if I love my enamoured owl one)
b) often horrendous shipping costs to good old Europe.
So! All you need is some adhesive plastic film (DIY stores have them), a paper cutter/exacto knife, an idea for a design (using the glowing white apple is tempting) and a lazy Saturday. (If your Macbook has a tendency to crash far more often than your old Windows machine, threatening its innocent fruit logo feels oddly satisfying.)