Looking for a home air filter? Help me choose!?

I was looking at the Sharper Image Hybrid GP Germicidal Air Purifier. I would get it for like 0. Which is 0 less than advertised. But i heard that they are NOT very good because they dont push enough air through the filter unlike other HEPA filters which supposedly do. Is that true? I also do know that they save a lot of energy compared to other brand filters and you dont have to buy 0 replacement filters every year. I need help please. Also can you please post some reference links. Thank you very much.