The Audiotechnica ATH-A700 Art Montitor headphones are a great $100 range pair of headphones. They completely cover your ears, and have slight passive noise cancelling ability (they muffle outside sounds). They are comfortable, and have an innovative one-size fits all (not adjustable) design.
The sound quality of these headphones are great. The headphones are stated to come with custom design low-end drivers, which boost the low end frequencies. This seems to be true, since in other headphones have tried the bass is unboosted. However, the bass is incomparable to some BOSE headphones, since it seems they just crank up the bass on their headphones.
The sound is very consumate and surrounding. Whenever I am stoned, I can feel my whole body reverberating from the bass, and the midrange and high tones are very clear. There is a definite feel of "being there" whenever these headphones are used. It is almost as if one is transported to a studio.
The only weak points are is that the bass end is not as powerful as BOSE headphones (if that is what the buyer is looking for) and that sometimes, with lower quality sound sources, the high end can be piercing.
These headphones are definitely worth the money, but there are more expensive headphones you can get.