Wayfair offers Weisberg Toddler Bed Rail for $42.99 (orig. $102) with free shipping.

Product Description:
This toddler bed rail is just what you need when you convert your baby crib into a toddler bed. It combines sleek lines with a powder-coated neutral finish over steel, along with an arched headboard and rounded corners. What’s more, it comes with a left side guard rail and a right side guard rail, so works with varied bed configurations. While this bed rail is part of a collection, it works with most design schemes from farmhouse to contemporary. Assembly is required.

• Traditional design metal toddler guardrail designed with vertical slats and a middle opening.
• Durable metal construction with a non-toxic matte black and gold finish.
• Converts the 4-in-1 metal convertible crib into a safe toddler bed (sold separately).
• Ships in one box. Some assembly is required, hardware included.
• Shipping Dimensions: 54.88" l x 19" w x 2" h. Gross weight: 11.66 lbs.