Why in the hell does it cost $20+ per AC HEPA filter? Just seems crazy to me. Is there any way to get these things without making my wallet weep? I rigged a box fan I had over the weekend with a matched in size 20"x20" HEPA AC filter on the back side of it and ran it on high in my bedroom. When I woke up this morning I was very surprised with how much better I felt. Didn't have the usual irritation in my throat, nose and eyes that I usually have. With results like that I figured it'd be a good idea to do a HEPA filter for my homes AC as well but it's just so damn painful how much they cost.