Honestly, I would be quite surprised to find a decent pair of headphones (sound and comfort-wise) for less than $100. For less than $50 you can probably get something light and comfy, but it'll be crap for sound quality and isolation. Or you can find something that isolates well, but squeezes your brains out your nose and sounds like the inside of a garbage can. But once you hit the $100 mark, then you start to have some real choices. I've had three pairs of MDR V6's, and for the money, I have yet to find anything close in terms of sound, isolation, and comfort. BUT - Sony has turned the physical *quality* of these headphones into utter garbage. The first pair I had lasted 10 years with pretty hard abuse. The second pair made it 2 years before literally falling apart. They also changed the material used to make the spiral phono cord into that horrid Sony patented TangleMatic crap that got so bad that I finally chopped the damnable thing off and put on my own shorter straight cord, as any 'studio monitor' should have in the first place. My third pair is already dying (cushions) after less than a year, and the cord is getting snipped this weekend.
The sound range on the V6's is incredible for the money, but damnitall, Sony has dropped the ball on quality and that alone makes them a poor choice today.