Wow - those MountainAir filters are pricey. Best I can find is $190 for the 6" variety. I'll spring for one of the higher end units if that is what it takes to get the job done. It's rated for 3 years of use so it should keep me going a good while as I wouldn't use it full time.

I'd love to save a few bucks if I can. Anyone using a cheaper option please chime in!