I suffer from pollen allergies and after much Googling and forum conversations a few years ago I bought one of these for $450, just now wanted a second and found them on special at $249 + $20 shipping.
At just under $500 its the rolls-royce of home air purifiers and I was reasonably happy, fewer bouts of hayfever and the lower dust level is great for the electronics.
its always this price…. i bought one back in december 2014 for $269 shipped….