Focus on the Bill of Materials (BOM). Ask the supplier which Bluetooth chipset they use (e.g., Airoha, Jerry, or Qualcomm), as the chip accounts for a large portion of the cost and performance. Negotiate a staged payment term, such as 30% deposit and 70% balance after third-party inspection but before shipment. For long-term partnerships, request a 1% - 2% spare parts allowance (extra units) to cover potential RMA (Return Merchandise Authorization) issues, which is more cost-effective than shipping single defective units back to China.