i think i spent about $100 or so on my active air 140 cfm fan and about close to another hundy on the phresh filter i have.. best money i've ever spent.. my first grow was super skunk by g13 labs, and i didn't have any kind of odor control for that grow, and the second you opened my front door, it smelled like two skunks were having butt sex in my grow room.. that smell was unbelievable .. after that shit, i had to get that odor under control, and nothing has helped like a good carbon filter and fan..