Reccomendations for a good air filter for people with allergies?

[circus_freak_rachel]

My fiance recently found out he has severe allergies to pretty much everything, but especially to dust mites, dogs, and cats (I own dogs and cats that stay indoors). We're looking for a good air filter that will eliminate all of these allergens, but without leaving a funky odor in the air like some do, or causing nose bleeds. And especially without breaking the bank! Of course we'd rather invest in a good one that will work, but still preferably under $200, and for a larger room. Any reccomendations, other than getting rid of the pets as that isn't a possibility? Thanks.