This Ionic Whisper Air Purifier And Ionizer is on sale for $21.99 at Woot. Shipping is free with an Amazon Prime account or when you sign up for a free Prime trial. Otherwise, it adds $6. Even with a shipping fee, that's the best price we could find by $5. It features two operating modes and a permanent filter that does not require replacement. Please note that you will need to log in with a free Woot account, a free Amazon account, or your Prime account to get this deal. Sales tax is charged in most states.