Air filters can be very expensive, especially if you purchase one that is made for homes with allergens, pets, or smoke. You can buy a cheap air filter for your HVAC system for a round three or four dollars, but they really don’t help to remove harmful pollutants and allergens from the air. My wife and I have mild allergies, so we purchase an air filter that is made for allergy stuff. Instead of spending $4, my wife and I spend $11. It’s a huge amount of money, but the allergen reducing air filter works better than anything else on the market. My wife and I have been ordering our air filters from an online distributor. We order the air filters six at a time in order to save the most amount of money. If I buy a single air filter at the home improvement store, it’s usually $11. When I buy a six-pack from the online distributor, they are only $7 each. I also get free shipping. The last time that my wife and I ordered air filters, they sent us the wrong size. The air filter had the right size printed on the side, but it did not fit my machine. I contacted the manufacturer so they could replace the air filters. I found out that there was a problem in the factory and a whole lot of air filters were stamped with the wrong size. The company replaced my order free of charge and they sent the new air filters overnight express. We certainly couldn’t complain after that customer service.