I have two of the Sharp Air Purifier's. They will run about $499 a peice. There was a good threat a few weeks back with this very same question asked...let me try and find the link. But I like these ones because you don't really have to change any filters. If you get teh less expensive ones they fuck you on the constant purchase and cleaning of new filters. So just go for the more expensive one and saves alot of time and money in the long run. Let me try and find that link for you...