Sterilite 4-Shelf Shelving Unit (Platinum) for $29.99.  Here is a screenshot for your reference.  Shipping is free on orders over $25.  If needed, use this Filler Tool to pad the order for free shipping.  The shelf storage is made of plastic with tubes with each shelf holding up to 150 lbs.  It measures 34.5"L x 14.375"W x 57"H.