With so much smoke around at the moment this may be useful for some people.
Bing Lee is having a sale on Dyson Pure Cool towers (current model) for another 9 days, and it's reflected on their eBay site. The bonus with the eBay listing is that there is another $50 off.
Description:
Automatically purifies a whole room, capturing 99.95% of fine particles such as harmful pollutants.
To purify a whole family room, the Dyson Pure Cool(TM) purifying fan goes beyond standard test conditions, by automatically sensing particles and gases, capturing 99.95% of ultrafine particles, and projecting & and circulating purified air using Air Multiplier technology.
Quick list of features:
Senses pollutants in real time
360° sealed HEPA
Intelligent reporting
Air Multiplier™ technology
Oscillates up to 350°
Draught-free diffused mode
Quick & easy filter changing
Night-time mode
Remote control
Quiet Mark
Certified Asthma & Allergy friendly™
Sensitive Choice® approved by National Asthma Council Australia
These were $599 at Costco a while back so may be worth checking there first.