Does anyone have experience or knowledge of inexpensive carbon monoxide monitors? I am looking for something low cost but still reliable. Of course there are scores of $10 Aliexpress ones, also on TradeMe, and most probably don't work. How is one to know? I also see a few on Bunnings and Mitre 10 and presumably they do at least meet national standards but I don't want to spend too much on this. It is just for reassurance. Ideally I would like to find something in the $30-$40 range. Don't need bells and whistles, just reliable detection. Recommendations welcome.