Cimo Slim Grip Case
If you're looking for a case that's tough and durable, yet extremely thin, the Cimi Slim Grip series is worth considering. They use a really thin layer of TPU material that's precision cut to keep the phone safe. It's not too thin though, and there are still small raised edges keeping the screen and camera safe.
It simply won't feel like a huge bulky case. This case comes in three different colors for under $8.