The Capcase one above looks like it's made of clear TPU. There are several TPU cases on eBay that you can find of different colors and patterns. They cost only a few dollars (USD) and usually come with free shipping.
If you prefer something clear with no patterns, there is a seller on eBay (by the name of 'dcmugen88') who sells two different colors. He has an 'Electric Blue' and a 'Smoked Black' TPU case available. He has a no-color clear one too (called 'Pattern Clear'), but it has a kind of tiled diamond pattern on the back. I bought the smoked black one several weeks back, and I like it very much especially since it doesn't have any kind of logo on it.
The TPU ones are flexible, protect very nicely, pretty thin, form fitting, and allow easy access to the buttons.