In my experience, there are certain price brackets within which quality is similar (excluding beats). Within each price bracket above low-end you will find headphones that you really like, and ones that aren't right for you. Sometimes there is a correlation to "quality" (beats = no) but a lot of the time it's simply preference. Of course, it is assumed that you properly listen to music - if music is something you like to "hear" and maybe like to use in order to isolate yourself when commuting, you may not notice much of a difference.

Once you look above $600 you will find headphones that are simply superb. And there are differences in the way that they sound, although as I said not much difference in "quality"- i.e. the variations give a slightly different sound to each model, which will appeal to individual preferences rather than (generally) being better/worse than another model. Comfort is also a factor, although all in this price range will sit on your noggin well, and again personal preference is a major factor.

The other important factor is your amp - if you're looking at mid-range headphones most decent amps will to be sufficient, but when you're looking higher up then you need to pair your headphones with the amp that best compliments their sound characteristics in a way that you like. But sometimes deliberate pairing can be quite worthwhile in the mid-range as well, especially if you are an intent listener.