perfect case for your DS Lite, you might want to check out these handmade options by eBay's munkybaby05. Made with yarn, felt, and plastic canvas, these cases are adorably geeky, and according to the seller, will fit snugly on any DS Lite.
There's two Metroid options, including the one pictured above and a Samus vs. metroid case. If you prefer the Legend of Zelda as your game of choice, though, she also has a case featuring Link and another with a sparkly Triforce.
The cutest of all, though, are the Mario-themed cart cases, which are shaped like little boxes and can hold about nine or ten games. The game holders are available in red mushroom, green mushroom, or question block designs.
Currently they're not too expensive for handmade items ($18 including shipping and handling for the DS Lite cases, $11 for the game cases), but of course, you never know with eBay.