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No clue regarding active noise cancellation. If you're okay with passive (aka, they go on your head and keep sound out just by virtue of surrounding your ear), a few popular low-cost options include the Audio Technica ATH-M50s and Sennheiser HD280Pros. Everyone in the audio world has their own opinions on this sort of stuff, but I've owned a pair of each of those and, despite their small flaws, both are decent pairs of cans.

The only time you really want the active stuff is when you're traveling and there exists a lot of low-frequency noise, such as on a train or airplane. Looking around on Hydrogenaudio confirms that the QC are okay if that's all you need, and also that alternatives exist, such as IEMs, which might have a wider range of use as they simply have very heavy passive isolation.

[jordanthoms]

I brought a pair of Sennheiser PXC-450s - they are nice in that you can turn off the noise cancellation and use them without batteries (and get a boost to the sound quality by doing so), but if you are on a plane or just have loud neighbors in the office I can turn it on and cut down on the outside noise. The cancellation itself isn't quite as good as the QuietComfort ones but it's close enough.

[niels_olson]

The only time you want ATH-M50s is when you're cold and want to feel your ears sweat. I break them out on occasion for close listening to something or other, but holy crap, they're miserable. The Bose QC-15s go for hours at Starbucks while studying. I'll probably buy a pair for each of my kids when they go to college.