My launch 3VO has been rocking a cheap, TPU case for 11 months. It holds its own shape, fits snuggly around the 3D, leaves all the ports open, and most importantly MY 3VO IS PERFECT AFTER DOZENS OF DROPS.
No screen/body damage.
They don't sell the one I bought exactly, but an updated version..
http://www.amazon.com/TPU-Cases-Fle...WDO0/ref=sr_1_9?ie=UTF8&qid=1336698560&sr=8-9
I'm not into otterboxes or cases that cost more than $10 frankly. Nothing made out of plastic/rubber/silicone that small should ever cost more than that.
The only caveat is you drop your phone's screen directly onto a sharp edge, which I've never done. Mine usually falls out of my lap or onto the ground, and I pick it up and its fine.