Walgreens has the Clean AirBall CAB011 Portable HEPA Air Purifier - White (also Blue
) on sale for $25 - 15% off with coupon code FUN15
[Exp 3/31] = $21
with free shipping. Normally around $50. Features HEPA filtration which removes 99.97% of particles at .3 microns and a noise level rating of 32dba.