Like much of the other sporting equipment on the market, snowboard bindings are constructed to be as light as possible while maintaining the strength and responsiveness needed to perform. The most expensive bindings use more high-tech materials that shave weight while maintaining performance.
The main structure of a binding is the base plate. Essentially this is the bottom of the snowboard binding which you stand on and is secured to the snowboard using a plastic mounting disk. Since the base plate is the bulk of the structure and most important single piece of the binding the materials used to make it vary the most. The least expensive bindings on the market use a plastic base plate. Higher quality bindings use an aluminum or composite base plate. Composites vary widely by brand and include such materials as glass/nylon, carbon fiber or fiberglass. Many bindings use EVA padding that attaches on top of or is built onto the bottom of the base plate. This helps to provide enhanced response and cushion landings.
Attached to the base plate are straps. Most bindings today use two straps, one on the ankle and one on the toe. Each strap has two sides, an inexpensive plastic ladder strap and a padded EVA foam strap with mechanism to tighten, usually a ratchet. The ratchet may be composed of aluminum or plastic depending upon binding. Aluminum is the more quality, durable option.
The back of the binding which presses against your calf and provides support and response, is composed of plastic or composite material like polycarbonate. The backs usually include a layer of rubber or EVA to provide some cushion on your leg. Some bindings have a heel cup that is a separate piece, attaching the base plate with the high or low back. Like the other pieces of the binding this can be aluminum, plastic or composite and may be different a different material than the base plate or back.
While fancy high-tech materials may sound sweet and might provide some noticeable enhancement for serious advanced riders, average riders probably won't benefit that much from these materials. In the end, the snowboard binding is still a means of keeping your feet attached to the board. More important aspects to consider are the fit of the binding with your boot, how comfortable and easy to use the binding is and the features you desire. Only if you're looking for the lightest, most responsive binding without a particular price limit will you really begin to seriously consider materials used.