Small space, big ideas

Now that we are actively shrinking our living space to make more room for work, I've started paying even more attention to space saving ideas. I'm not naturally inclined to economize on space so this has been a challenge for me. I've come across a lot of really wonderful things but since cost is a big issue too it's meant more limitations. We know we need shelves, but we don't have the room to do what we want, like this:
I like that these shelves look both sturdy and light--we have a large number of books and many of the options I've seen seem more tailored for sparse decorating than actual usage. And I love the open door, the sunlight on the floor tiles, the color of the cabinet...
I love the little step for these shelves:
It almost disappears against the while flooring. (Both pics are from Living at Home).

What we will probably settle on is something much much simpler (and cheaper) until a better option comes along. Clean, airy yet sturdy is what I'm going for. And then I'll just get back to dreaming about built-ins.