Way Basics spent ten years perfecting the building block of their products - a material they call zBoard made from post-consumer recycled paper and weighs 62% less than particle board. zBoard is water resistant and boards can be held together with strong adhesive strips. We've watched several assembly videos on YouTube produced by the company, reviewers and customers and they truly are easy to put together (unlike certain Swedish products, ahem, that have brought many people to the brink of insanity not to mention couple's therapy).
Way Basics sells single cubes in two sizes and eight colors (both less than $25) which you can combine in a variety of ways or purchase two or three-shelf versions. They also sell a table base and tabletop (in either a square or rectangular size) which can be used with cube singles doubling as chairs.
If you're looking for versatile shelving and storage for children's bedrooms or playrooms, Way Basics is worth a look.