Air purifier suggestions for people with cat allergies?

Wiscasset ME

Description

Can anyone suggest a really good (but not too expensive) air purifier for someone with cat allergies? I already take a daily antihistamine but would like to cover all my bases. I would like to get one for a small room (150 sq. ft.) and another one for a much larger room (650 sq. ft.). I have looked on Amazon but most of them have a ton of good reviews and it's hard to tell the difference (besides price). If you also have allergies and have found something that works well for you I would appreciate hearing from you. Also wondering if anyone out there has had any experience with Allerpet or some similar product, and if so what your experience with that has been. Thanks!