What do you know about air purifiers?
Looking for an air purifier. Saw one at Target that never needs a filter change–you just vaccume it when its dirty. I’d like to buy it so that I don’t have to continually buy filters but will this work as well as others? Forgot the name of it but if anyone has this type can you tell me about your experience with it?
Also they all advertise that they have "quiet operation" but which ones are really quiet?
Can anyone recommend a good one?

I have tried several and have 2. I have the Ionic Breeze from Sharper Image and it does an OK job in a smaller room. You have to clean the collection plates with a wet paper towel about once every 7-10 days (only takes a few minutes). I also have an Oreck XL with Silent Technology and it seems to work better. You have to rinse the filter when the little light comes on to tell you it’s dirty. There are 3 fan settings and you can have the ionizer on or off. I have that one in my bedroom because of my allergies and at night I set it on silent. You can still hear it but it is very quiet and doesn’t bother my sleep.