While the case isn't yet ready for sale, Lootiful already sells a smaller version for the iPhone 4 for a reasonable $18. You can pre-order the case “soon,” though. And with Nintendo's continued refusal to put its games on non-Nintendo hardware, this might just be the closest you'll get to playing Mario on your iPad. At least until Nintendo is forced to pull a Sega, I guess.
iPad 2 Game Boy case [Lootiful via TUAW]
source: Gadget Lab