Good Air Purifier?

What is the best air purifier for removal of dust and odor? I have been looking at ebay and is almost convinced on buying ecoquest (with hepa, uv, ionizer, and ozone generator). The only thing that still prevents me fom buying this ($219) is the ozone generator which can induce asthma. I am an asthmatic. Anyone with a good experience with a VERY GOOD air purifier? I can only afford <$300 and does not consume much electricity, with low maintenance. Thanks.