Let me put in a word for the MB Quart QP805HS. I bought one off of eBay on a lark for $80, and when I got it I was absolutely blown away by the sound -- it bea

Let me put in a word for the MB Quart QP805HS. I bought one off of eBay on a lark for $80, and when I got it I was absolutely blown away by the sound -- it beat the pants off my Sennheiser HD-590. The QP805 is a closed-back design, and despite the 300Ω rating, plays just fine off a laptop or iPod. It's reasonably comfortable, with good isolation. They show up on eBay from time to time (I see a couple there now). If you want amazing sound for less than $100, I don't know anything better.