Yesterday I finally clicked Add to Cart on a new humidifier filter, and, to be real, I was half-convinced I really needed to purchase this (the app said I needed a replacement). The replacement showed up FAST, fit right into the humidifier, and literally the smoothest progress ever.
For context, I use my humidifier 24/7 at 30% humidity, and around the 7 month mark it needed to be replaced. Paying around $17-20 biannually isn't a deal breaker, so I don't think the price is unjustified - even though it probably costs Blueair $0.60 to make them. OH WELL! I'm a happy customer.