When it comes to air quality monitors, accuracy is the most important performance criterion. Using data from independent tests by South Coast AQMD, the correlation between air quality monitor prices and accuracy was analyzed by looking at the accuracy of PM2.5, one of the most common air quality parameters. Surprisingly, the analysis showed that the price does not seem to affect the accuracy of the monitor. Monitors priced between $100-$200 seem to offer the best accuracy, while more expensive monitors may have additional features such as measuring multiple air pollutants or better connectivity options, but the accuracy for PM2.5 is not necessarily better.
https://www.airgradient.com/open-airgradient/blog/expensive-air-quality-monitors-not-more-accurate/