Air Purifiers

In the past we bought this stuff for a box and got (3-4?) cut pieces out of it. We bought it at Lowes in Burbank, CA. But, we've moved to a new city and don't know where to find it locally. The local hardware stores don't seem to carry it and I'm having a hard time finding it on-line. Could be because it's late and I'm tired and my "google-fu" is weak right now.

This looks like the air purifier that we have and be the same model:
http://www.amazon.com/Whirlpool-Whispure-450-Purifier-AP45030S/dp/B000ELQMPM/

I'm not looking for the whirlpool brand since it appears to cost about three times as much. I'd rather pay a fraction of the price and cut them to fit just as we have since we bought the darned thing.

Can anyone point me in the right direction???

I have a HEPA air filter. It has a button on it, which turns on the optional "ionizer" feature. The system is made by Honeywell (actually a company called Kaz, which sells it under the Honeywell name.)

Any information on the helpful effects of having "negative ions" in the air?