When sourcing kites in bulk, prioritize Ripstop Nylon or Polyester for the sail material, as these fabrics prevent tears from spreading and offer excellent UV resistance. For the frame (struts), Fiberglass rods are ideal for beginners due to their flexibility and low cost, while Carbon Fiber is preferred for professional or stunt kites because of its superior strength-to-weight ratio. Ensure the connectors are made of high-density polyethylene (HDPE) to withstand high wind pressure without cracking.