I went to Walmart looking for an alternative to the $30 cabin filter. I found a hepa filter that is almost perfect. It is from a Hamilton Beach room air cleaner. It is called the Hamilton Beach TrueAir filter. Part # 04712. It is with all the other house and air cleaner filters and costs $10. It looks just like our original filter but with cardboard sides. Height and depth is perfect but the width is 1/4 inch too long. You do have to modify it slightly. I took off the right side wall so it could flex in order to fit it in its space. The original filter required a bit of flexing also. That seemed to do it. I have tried it for 3 months and all is well. I checked the amount of air coming out of the vents before and after and it seemed the same. On the next one I will try to slice the center in the front and the back so I can compress it 1/4 so it is the exact same size as the original and still has the sides.