I like humidifiers they work well only thing is they can breed some pretty nasty stuff if you don't look after them. If you keep them clean and the pads changed they can be a great investment. Aprilaire is one of the better units for the money, there are alot more on the market but they are pretty good. As for the filter thing you need to asses what your quality needs are, so you can weigh them against the costs. Electronic Air Cleaners are great when installed and maintained properly if not they are the worst thing you would ever buy. As for the Hepa filters they are farely new to the market and therefore the price is still fairly high. There are lots of options out there I would take a look at some good web sites here is a few to start. http://www.aafintl.com http://www.theairfilterstore.com/ http://www.airpurifiers-r-us.com/hepa.html After you get as much info as you can and weigh your options compared to what you need you should be able to make a wise decision.