Sam's Club offers its members the Muscle Rack 4-Shelf Heavy-Duty Steel Storage Rack in Silver Vein, model no. UR361860PB4P-SV, for $33.88 with free shipping. (Non-members pay a $3.39 surcharge.) Outside of the price below, that's the lowest total price we could find by $3 and a great deal on this type of shelving in general. It measures 36" x 18" x 60" and features adjustable shelves with a 3,200-lb. total capacity.
Not a Sam's Club member? A close price, Amazon offers it for $35.49 with free shipping for Prime members.