I recently adopted 2 cockatiels from my girlfriend, and they give off a lot of dust, small feathers, etc. and I invested in a $50 Honeywell HHT-011 portable air purifier. It seems to be working very well so far. The foam pre-filter is already coated in small feathers, dust, etc. although the HEPA filter itself still looks perfectly clean. Has a built-in Ionizer feature and 3 different speed settings. I like it so far, but I've heard it has a LOT of energy consumption. It says it's only for small rooms, though. The filter is permanent, which is nice.