Product review (5 stars): Compare Prices before you purchase!
This seems to be the most economic pack available, however, I would advise looking closely before buying individual replacement filters, especially the A200 Hydrocell kits. They are very expensive.  If you of the math, you'll notice that you can purchase a brand new AOS 7147 humidifier for less than some of the filters for it! If you're going to replace these filters every one or two months like they recommend, why not spend less money and buy a brand new humidifier with the new filters in it already? Right?

Not sure who thought up the price point for some of these filters but they weren't really thinking, or maybe they just think you're dumb enough that you won't look too hard.