Those aren't really "earbuds", in my opinion.
Earbuds just kinda hang in your ear, pointed in.
I would call these "canalphones", although that term isn't often used. They create a seal and stick into your ear canal, creating a small, sealed chamber. The sound quality is - potentially - amazing. Good bass response, typically a major issue with "earbuds", is possible. Plus, you block out WAY more sound than is possible with any other design, including noise-reduction phones.
I wouldn't pay >$400 dollars for any set of headphones myself, but to me this is no more ridiculous than similarly priced full-sized phones.