When comparing prices, the most critical technical factor is the flow rate range (typically 2-60 L/min or up to 80 L/min) and oxygen concentration accuracy (should be 21% to 100% with ±3% variance). Higher-priced units often feature integrated air-oxygen blenders, built-in humidification systems with precise temperature control (31°C to 37°C), and high-performance turbines that do not require an external medical air source. Ensure the device includes real-time monitoring sensors for FiO2, flow, and temperature to justify the investment.