What Is The Best Air Purifier For Under $200.00.?

I just moved into a garage apartment in which no one has lived in for quite some time. There is dust everywhere, as soon as I go into the place i start sneezing from the dust, so I'm looking for a really good air purifier for under $200.00 that will eliminate all this dust from the air. As well as mold, pollen, ragweed and other particles. What is a good brand and where can i get one?