The price of sandpaper is primarily driven by the abrasive material, grit size, and backing type. High-performance materials like Zirconia Alumina or Ceramic are more expensive but offer superior longevity for metalworking, whereas Aluminum Oxide is the cost-effective standard for woodworking. The backing weight (ranging from A-weight paper to X-weight cloth) significantly impacts durability; cloth-backed sandpaper typically commands a higher price due to its tear resistance in machine sanding. Additionally, ensure the product features an anti-clogging (stearated) coating if you are working with paints or softwoods to extend the tool's lifespan.