I have one that cost me $30 all in and you can't hear it at all on the lowest setting (but still decent airflow when you put your hand down). Honestly the biggest benefit in my home environment is how much it has killed the fungus gnats living in my plants. I checked the filter after running it for a few weeks and it still looked relatively clean, but probably a thousand dead flies were in the bottom of it too. I have taken other measures against these flies with not much success (vinegar traps, sticky paper, watering from the bottom, mosquito bits designed to kill larvae, I tried everything I could find one the internet to no help).