I was looking for one of those a while back but gave up because (in my opinion) they are too expensive for what you get and they just didn't have what I was looking for. I am actually thinking about making one similar to the unstrung hard case Three Rivers sells. If you don't feel like actually making one, I am sure you can search around and find someone nearby who is handy with a saw that you can give your specs/plans to and they can do the job for you for much cheaper than you can buy one.
Matt