Garden bridges can serve a decorative or functional feature. Garden bridges serve as a pathway across a stream or pond, or over an area of your garden that gets muddy. Garden bridges used for purely ornamental purposes can be dressed up with climbing flowers, garden gnomes and sculptures as well as with plants. The most popular garden bridges are made of cedar, and pricing tends to vary based on how many rails and posts are included. Most garden bridges need to be assembled by the buyer. They are shipped in pre-cut and pre-drilled pieces and include straightforward assembly instructions. The most basic garden bridges (without posts and railings) cost about $350 to purchase online. A 4-foot lumber bridge with railings and posts with cost approximately $500 online.