A good material will cost more, and that is a fact. Parallel clamps have high-quality metal. Iron or steel increases the durability and longevity of the device. Moreover, when buying something for long-term usage, it should be of good quality and cost you more than buying something of a cheaper quality. Another thing is the product's confusability; for example – sandpapers are consumable as you will buy more when there is no more in your workshop. However, it does not work that way for a clamp as a good-quality device will last longer, and you will not have to buy another one. They are more expensive than regular cheap-quality clamps that most beginners use, but they do not last more than a few months