With the recent California fires, I've been looking for a decent option. Unfortunately the Elgato Eve sensor is no longer sold, and the few other consumer products still hover in the $100+ range with poor reviews.
PurpleAir sells an indoor sensor, but it appears to be limited release and somewhat 3D printed.
https://www.purpleair.com/
PurpleAir sells an indoor sensor, but it appears to be limited release and somewhat 3D printed. https://www.purpleair.com/