Ebay offers Refurbished Shark HE401 Smart Sensing Air Purifier for $149.99 (reg $349.99) with free shipping.

Product Description:
The Shark Air Purifier 4 quietly distributes air through 4 powerful fans. Clean Sense IQ technology tracks air quality & auto-adjusts power to constantly maintain clean air in your home. A Shark Anti-Allergen HEPA Filter captures airborne allergens, dust, dander, and particles. Advanced odor protection guards against cooking smells, smoke, and more. Cleans medium-sized spaces.
Features:

•  SHARK AIR PURIFIER 4: Air purification for the home, up to 1000 sq. ft. based on one air change per hour
•  4-FAN AIRFLOW: 4 high-speed micro-fans work together to evenly distribute airflow across the filter
•  ULTRA-FAST MEETS ULTRA-QUIET: Four high-speed fans provide a remarkably quiet clean, and an incredibly fast clean air delivery rate
•  TRACKS & ADJUSTS AUTOMATICALLY: Clean Sense IQ tracks air quality & auto-adjusts to constantly maintain clean air in your home, easy-to-use control panel displays data in real time
•  ANTI-ALLERGEN HEPA MULTI-FILTER: Shark's Anti-Allergen Multi-Filter captures 99.97% of dust, dander, allergens, smoke, and household odors
•  HEIGHTENED ODOR PROTECTION: An advanced odor guard on the filter protects against household odors from cooking, cleaning products, and more
•  ALL-DAY CLEAN AIR CONFIDENCE: Shark's revolutionary 4-fan technology combines with a real-time feedback display to give you clarity and confidence in the air you breathe
•  MEDIUM CLEANING AREA: 4 fans working together generate the power to clean the air in medium-sized open spaces
•  REMOTE CONTROL INCLUDED: An easy-to-use remote gives you complete control from up to 15 ft.
•  Based on HEPA filtration standards of 99.97% filtration, down to 0.3 microns