Can you really put a "price" on them? An Arai helmet isn't inexpensive. It isn't made to be.
And when you wear an Arai Helmet, it isn't made to feel good for just an hour or two. It's made to feel good all day, every day - and to keep feeling good for years, long after cheap helmets have become loose and shabby (and probably had to be replaced more than once).
You can't always see the reasons why an Arai Helmets feels better, but they're there: lower weight from aerospace fiberglass-based construction; a lower center of gravity for better balance and less strain; softer single-piece multiple-density liners (whose technology still hasn't been able to be copied in almost 20 years). Ventilation systems that work in the real world, not just in drawings. A helmet with no "minor" parts. And the result is major: you just feel good. You want to keep riding.