It may well be amazing engineering, but $399 for a hair dryer? The only scenario I can imagine in which I would spend $399 for a hair dryer involves USD hyperinflation.
Professional hairdryer go up to $200, so $399 isn't that much of a stretch for something new like this Dyson hairdryer.
Why not get two professional hair dryers instead?
This is a consumer-grade dryer. They specify it in the pricing section. If I were a stylist I wouldn't hesitate to drop $400 or more on a good fast dryer.