[sbr464]

https://www.co2meter.com/collections/sensors has a bunch of different ones, I usually look on Mouser also. I don't have a name of one currently. I've been using the particle.io platform with a particle device/LTE for sending out data and programming them.

[gsich]

None of them are in the 8$ range. There also seem to some copies which are way overpriced.

[sbr464]

Interesting to have an arbitrary $8 price point. You only live once, get the best!

[gsich]

Not my restriction.