Foam pool floats are often expensive because they are made with a high quality, durable foam material that is designed to last a long time. This foam is often UV-resistant, meaning it won't fade when exposed to the sun, and it is also resistant to chlorine, which helps it last even longer. Additionally, the foam is often thicker and more dense, which provides extra support, comfort, and buoyancy in the water. All of these factors can contribute to the higher cost of foam pool floats.