So I've written a post on how I built a case for my Raspberry Pi for about five bucks (not including the paint) using off the shelf parts from a hardware store. You can read that here if you like: http://stinebaugh.info/my-five-dollar-r ... ase-build/
It's built out of some PVC Electrical box covers, some nylon spacers and some careful placement of the holes so the spacers sit tight to the USB port and help hold it in.
Here's a peek at what it looks like.
There's alot more pictures and info on my post, and I hope it helps someone build a nice and sturdy case for not alot of money. Enjoy!