Looking for opinions on which filters to buy for my HVAC system. The last year or two, spring has really kicked my rear in the allergy department. I've always bought the cheap pleated filters (3 pack for ~$9 at Lowe's/Depot) and my setup requires two 12x24x1 filters. The cheap fiberglass filters just seem too subpar and remind me of a K&N on a car... So my questions are: *Is it worth it to invest extra for the premium allergen filters? *Do they really work? *Are they harmful to the system in any way (more restrictive airflow)? *Are there any good options for <$10/filter? *Should I consider a completely different air filtration method? And the more interesting question: Would it be better to use two allergen filters at the same time, or just one along with a standard pleated filter (considering filtration, airflow, and effectiveness)? Thanks in advance!