You should expect to pay anywhere between $25 and as high as $10,000 for a garden trellis. For instance, you can find small metal cage trellis for about $25 to $50. On the other hand, a fully built garden gazebo trellis can cost as high as $10,000 or more based on the material, size, and design. Similarly, you can spend more or less if you choose to build your own garden trellis. This is because you will still have to consider the materials, amount of materials, size of trellis, and design of the trellis.