They can be if the artists release MusicPac's. For example, Amy Winehouse's Back To Black has sold 120,000 copies, yet most other artists can only manage 50,000 copies to be considered huge (Blackout, Hard Candy, The Dutchess for example).
CD's come in a cardboard sleeve without the booklet, there's only a piece of plastic inside to hold the CD and the cover/back cover outside, a pretty cheap product all in all.
