A shelf apparatus includes first and second upstanding posts each having a plurality of horizontally-extending grooves in an external surface thereof, the grooves spaced vertically from one another. First and second shelf support clamps are supported by the first and second posts, respectively. The clamps each have a clamp body received only partially about its corresponding post, and the clamps each include a horizontally-extending protuberance such as a rib received in one of the grooves of its respective post. The apparatus further includes first and second shelf brackets supported by the first and second clamps, respectively, and a shelf supported by the first and second shelf brackets.