Griffin Reveal Etch Ultra-thin Protective Case for iPhone 4, Black
My husband had bought a Griffin case at a retail store and I liked it.  I shopped at Amazon and got the same thing but 1/2 the price with shipping.  The only problem was that the opening for the switch to turn off/on the volume doesn't reveal the entire switch.  The opening was not cut properly but you are still able to move it.  If not, it would have been perfect!