Walmart offers the Coway Mighty True HEPA Air Purifier in White for $161.99 with free shipping. That's $18 under our April mention of another color and the lowest price we've seen. (It's also the best deal today by $18, although most retailers charge $223 or more.) Buy Now Features 4-stage filtration system HEPA efficiency rating of 99.97% air quality indicator with particle sensor ionizer