I had a whole bunch of CPU's laying around and went on the internet looking for Clam shell cases. Apparently these cases must have a small amount of gold in them because everywhere I looked they were crazy expensive.
I found this eBay page which sells 12 of them for $8.99 with free shipping which brings them down to .74 cents per case which is the cheapest i've found anywhere. They also arrived quick too.
They worked perfect!