How much are carbon monoxide breathalysers to see if you been smoking?can i have info on it please thx!!?

how much are carbon monoxide breathalysers to see if you been smoking?can i have info on it please thx!! how much are they how they work where you get them from are the good any more info?! how much r they how long can u be before the smoke out of ur system nd the breataliser cant tell?