When comparing prices, the sensor technology is the primary cost driver. Zirconia sensors are cost-effective for oxygen impurity detection in argon, while Thermal Conductivity Detectors (TCD) are standard for binary gas mixtures. For ultra-high purity argon (99.999%+), you must look for Plasma Emission Detectors (PED) or Gas Chromatography (GC) systems, which command a premium price due to their parts-per-billion (ppb) sensitivity. Always verify the detection limit, response time (T90 < 15s), and drift rate to ensure the price aligns with performance.