Nikki,

A few ideas:

1) Have you considered getting your ducts cleaned?  I've had tremendous
allergic issues in my past two homes prior to getting a thorough cleaning of
the duct work.  This involves high pressure vacuuming of all the junk that
builds up in your ducts, as well as the cleaning of your air
conditioning/heating equipment.

We use Filtrete 1250 filters and feel that helps.  You can also get vent
filters, which probably help, but I wouldn't bother prior to having the
ductwork cleaned.

2) Ionic Breeze was ripped by Consumer Reports -- I'd go online to their
site and read their report.  Also, these ionizer devices tend to generate
some ozone, which can be irritating if you have any asthmatic symptoms.

Steve