At first glance, the shelves in the picture below look just like normal shelves:
They’re not. They’re actually individual boxes, stacked up.
The selling point? If you ever move you can just pick up your boxes and go. The downside, other than the fact that big boxes full of books are heavy, is that these boxes are $40/each. That means a wall of boxes would cost approximately four million dollars (give or take; I didn’t go the math).