Cheap Air Purifier

Do those silent air purifiers really work? If you’ve purchase one of those silent air purifiers, could you share whether you thought it was worth it? I wonder if this will help w/ allergies. Thanks for any advice! I have heard both yes and no http://www.ezinearticles.com/?Air-Purifiers:-Worth-The-Cost-Or-Not?&id=142974 http://www.negative-ion-generators.com/Consumer-Reports-air-purifiers.php http://www.wholesale-suppliers.net/health-wellness/health_wellness_293.php However my mother has one and swears [...]