Marina wrote:
My sister says she needs a special air filter for her Trane furnace/air
conditioner.
(that's all the info I got from her).

The technician came out to measure for a filter today and said it would
cost $700. She needs extra filtering due to asthma and lots of dust in her
house.

I'm hoping there is a good site where the cost is a little lower and you
know they are a good honest site?
Thanks.
Marina

I've used http://www.iaqsource.com/ before with good results. I saved a
bunch of money buying new filters for my Space Gard system.
You'll need to make sure you match up your part numbers and everything
properly because you might end up wasting money if you buy the wrong
thing.

-Nathan

Look into Trion Air Bear, April Air Spaceguard are good media but the
enclosure does not seal well and replacement filters are alot more. 700$
sounds like a dual filter, UV and media or similar, or a rip off.