Yeah looking mainly for not just cheap but also reliable.
And if there is an asbestos checker detector I might need one too.
I found a $4.31 AUD carbon monoxide detector in aliexpress but it seems to cheap to be true so came to ask here if there was any way to verify it's legitimacy or accuracy.
Get a professional to come in and test for you. Why would you possibly risk your's and others health/life?