I have been impressed enough by the value of a cheap pair I have of Sony noise-canceling headphones (model MDR-NC40) that when the first pair broke, broke*, I bought another, and am still happy with the investment.
Right now, I see them at Amazon for about $80 (http://www.amazon.com/Sony-Ultra-Lightweight-Foldable-Canceling-Headphones/dp/B001FXXAP8 -- the reviews there are poor, but they don't match my experience); I paid more than this for my first set, and less (about $60) for them the 2nd time around, thanks to a sale at Radio Shack. I briefly saw them on sale for about $25 at a Target store as well ... so, shop around ;)
I find them comfortable even over my glasses, which is unusual. (Not as comfortable as some of the best I've tried, expensive Beyerdynamics or Sennheisers, but surprisingly good, even on long flights.) The noise reduction is good, though not the world's best. ("The world's best," frankly, is something that I must admit I don't often think is worth the marginal cost -- your mileage, and budget, may vary.)
They fold into a nice small case, which fits well either one of the small outside pockets on my Tom Bihn Checkpoint Flyer, or the smallish Jansport backpack I'm carrying on my current trip to Seattle. I think they pay for themselves in flying comfort in one trip. Use a single AAA battery, which lasts for something near 20 hours.
* My fault -- I let them get pretty jumbled / crushed in a full pack, rather than take the few seconds it takes to pack them neatly in their case. It was a touch disappointing, but not strictly speaking the fault of the design; I'm pretty tough on headphones, and the 2d pair has been holding up well.