We wanted to share this with anyone who has been suffering with allergy problems and doesn't have a mint to spend on an air filter.

http://www.onlineallergycenter.com/articles/room_air_cleaner.htm

Room air cleaners help with allergies by helping people live in cleaner, healthier environments. By sleeping in a room with an air cleaner, you will breathe much cleaner air all night long. And by also having an air cleaner in your office, or any other room where you spend a lot of time, you will maximize your clean air intake and minimize the allergens you breathe. Even if you have a good filter on your central air conditioning system, a room air cleaner will increase the purity of the air you breathe. You can put together a very effective and inexpensive air cleaner by purchasing two items at most home improvement stores.

1. Buy a 20" square box fan (under $20) and a 20" square 3M Ultra Allergen Filtrete 1250 (@$18). It is very important to get this exact filter.
    
2. Place the filter on the intake side of the fan and flush with the fan with the Air Flow Arrow pointing toward the fan.
    
3. Attach the filter to the fan with a rubber band or tape.
    
4. Turn the fan on high. It will draw air through the filter, thus cleaning the air of mold spores, dust, and pollen particles. It will filter particles as small as bacteria.
    
5. Keep the fan running all the time, 24 hours a day in a closed bedroom. Run it at night at an acceptable noise level for you. Direct the flow of air directly at the patient when the room is occupied. You must close or block any air-conditioning duct. To cool or heat the room, set the fan in the doorway (air blowing into the room), and leave the door open enough to allow the fan to sit there (about 20"). When you are not sleeping in the room, keep it closed up completely with the fan running at high speed.
    
6. In 1 or 2 months, replace the filter with a new one. Your monthly cost for filters will be about $7-8. A washable, reusable electronic filter can be purchased for about $50, but they are actually less effective than the 3M Ultra Allergen Filtrete 1250. Custom sizes for your home can be ordered directly from 3M Company at 800-388-3458.