Deviantart can (rarely) be a source of high quality design materials. I would never rely on it, but its always worth a quick search before you go out and buy rights from a site selling stock materials.
Be sure not to use anything licensed only for personal use. You'll find alot of that; but many uploads(these for example) are often completely open source.
DVD Case+Art - PSD file by `manicho on deviantART
DVD Plastic Case Template PSD by =Jeno-Cyber on deviantART