Cases, clear covers, folios, nah. How about a Game Boy Color decal for your iPhone? Yes please.
This isn’t a cheap sticker from the office supply department, it’s ‘vinyl powered awesomeness’ and rated 5+ years of wear and tear, just apply it to the back of your iPhone. It also comes in other colors, as well as a classic Nintendo controller. Etsy is selling them for US$6. Now when you play those NES games on your jailbroken iPhone, you can look legit!