Hoover SilentAir 2000 Air Purifier $39.99
"Captures Microscopic Irritants - such as viruses, bacteria, airborne mold spores, pollens, dust, tobacco smoke and animal dander. Energy efficient and lightweight (3.5 lbs.). No Fan, Motor or Moving Parts - no parts to wear out or break-down. Room Capacity - up to 250 sq.ft."
Note that since this air purifier does not have a fan, it won't move air - which means it isn't as good as some of the more expensive air purifiers.
Link to Hoover SilentAir 2000 Air Purifier for $39.99