IKEA — EXPEDIT
An Apartment Therapy workhorse, the EXPEDIT series is a classic and IKEA has taken advantage of its immense popularity and expanded it in recent years. With multiple shapes, sizes and colors available it is a great option for lightweight, sturdy shelving. While BILLY is also a budget-friendly (though more traditional) solution, EXPEDIT is much sturdier as a freestanding unit and offers greater flexibility and multiple uses.
CB2 — Go Cart Series
The most design-forward and colorful of our list, CB2's Go Cart series is also the most expensive — but their largest shelf in the series is the Carbon Three-shelf Table that is $129 (and the white version is currently only $99). Go Cart has been around as long as CB2 and the line evolves and changes periodically. At times, they've offered small rolling cubes, towers and other colors. Currently there is also a Go Cart Desk. This is sturdy metal furniture that will last a long time and is truly adaptable to many uses.
Crate & Barrel — online only options
On the Crate & Barrel site there are a number of shelving options that are online only and they are the most budget-friendly of all their shelving products. Choose from wood, chrome and white metal shelves in a range of sizes. Good options for lightweight books, bathroom storage or making better use of the hall closet, these shelves are priced around $100 each. I like the simplicity of a Chrome 4-Shelf Unit for $109 in a bathroom or a series of 5-Tier White Shelf (also $109) for all-purpose storage in a mudroom or laundry room.
Exactly as the name implies, these shelving systems are way basic. Made from recycled paper, the zBoard furniture is exceptionally lightweight, sturdy and amazingly cheap — its downfall is that the weight limit is on the low side. I like the Madison Bookcase ($89.50) the best but their are fun, cheaper options like the Triple Rectangle Plus in Green ($29.99). Strong enough for most uses, Way Basics are ideal for kids' rooms, and nooks that you need some bonus shelving. As an added bonus, Way Basics are completely recyclable.
Home Depot — Workforce & Edsal Steel Shelving
Though lots of Inexpensive Industrial Shelving is available at a range of hardware stores and big-box retailers, a quick search revealed that Home Depot has an easily accessible collection of options from Workforce that are budget friendly and hold an incredible amount of weight. A cheaper option than commercial Metro shelving, industrial shelving looks even more utilitarian (perfect for today's trendy vintage industrial looks) and is ideal for heavy stuff like book collections, kitchen equipment, electronics, aquariums and immense rock collections. Try Workforce Heavy Duty 5-Shelf Steel Shelving ($76.97) or the slightly smaller Workforce 4-Shelf Steel Shelving Unit ($55.78) or the slightly-more attractive Edsal 4-Shelf Galvanized Steel Shelving ($59.99) — these are so inexpensive their perfect for lining long walls with lots of storage. For more options see Best Product: Inexpensive Industrial Shelving.