So my parents need an Air Purifier for home use. Which ones can I go for? What I'm looking for: Average or lower filter replacement cost. Ability to work long hours. Good after sales (I've heard bad things about Mi) 'Smart' features not necessary. Should filter all bad stuff like PM 2.5 etc. Budget is around 10K max. Suggestions.? Also you can post your reviews of your air purifier here, we all like to read them. Thanks!