I spent 100 bucks on a carbon scrubber, I wanted something that would last me so i bought a profession grade filter. However, i can just buy the active carbon off line and change it out when i need to, initially it can be expensive, but long run it will last and u can just buy the carbon to re-fill it when it looses its scrubbing capability. I also didnt feel like building one, although it would have been cheaper.