The $300 is one of the most popular ranges because you can find astonishingly good sounding and well-built 'phones that compare to their $1000 brothers. Obviously it's up to you whether that's true or not. I personally can tell the difference, but can spare that kind of money? No, so to me it's not worth it. To others it is.
I could swing getting $1000 headphones, but then I'd feel bound to them. I just got some $100 Donscorpio Dolphins that I'm enjoying quite a lot. Part of the fun is trying out and enjoying different equipment.