Just bought a case on ebay called the Pi Crust, seller id is Pi_crust for £7.99. It is 7 pieces of laser cut plastic that comes flat packed like furniture. It goes together in seconds, the top is clear so you can see the R-Pi. Ordered it 2 days ago and it arrived in double quick time. PArt of the sale price goes to the Raspberry Pi Foundation too.
Check it out here - http://facebook.com/rPiCrust
I am really pleased with mine, all the holes are cut precisely in the right place and it looks cool too.