Hello!  My daughter has had excema since she was a baby.  She has now been diagnosed with asthma and had some allergy testing done.  I have been trying to do research to see what we can do around the house to help relieve some of her allergies.  I have seen that an air purifier is one thing that would help.  Are there any air purifiers that are better than others?  They range in price from cheap to expensive.  I would like to know what would be best for my daughter.  I don't want to invest in one that turns out not to help her at all.  Thank you.