Costco offers its members the Winix Washable PlasmaWave True HEPA Air Cleaner, model no. WAC5500, for $139.99 with free shipping. (Non-members pay an additional $7 surcharge.) That's the lowest total price we could find today by $40, although we saw it for $11 less in December. It features a washable true-HEPA filter, 3-stage filtration, PlasmaWave technology, and a clean air delivery rate of up to 350 sq. ft. Deal ends April 17.