Thumb Score: +27 Amazon has for Prime Members: Coway Airmega 400 True HEPA Smart Air Purifier (White, AP-2015F, 1,560 Sq Ft Coverage) on sale for $339. Shipping is free. Thanks to Deal Editor iconian for finding this deal. Coway also has Coway Airmega 400 True HEPA Smart Air Purifier (AP-2015F, 1,560 Sq Ft Coverage) on sale for $339.