Need help finding a noise-cancelling/isolating headphones that aren't too bulky for about $200

Do you not mentions IEM's because they are uncomfortable to you? If you want something small that block the most noise possible, and IEM would fit that bill perfectly.

If you do think that they are uncomfortable, try getting smaller ones. For bass, good looks, and lots of isolation, I'd recommend the Klipsch Image X10 at about $100 under your price. With the correct oval shaped tips, you can hardly feel them in your ear.

The X10 is actually a very reasonable option, but if you want the best isolation available, I would look into Etymotic. They can provide isolation that is on par with Noise Cancellation ( or maybe even better ) for practically a fraction of the price. Though you might have to use the triple flanges, which might not be extremely comfortable. the isolation sure makes up for it. The sound may not appeal to the mainstream crowd however.

SHORT VERSION:

-IEMs cancel the better than headphones.

-Smaller IEMs with better tips are more comfortable.

-The Klipsch Image X10 is the most comfortable earphone I've used.

LONG VERSION:

As you can see from the noise isolation graph, the Active Noise Cancelling (ANC) Bose Quiet Comfort 15 at $300 does the worst job at stopping noise compared to the $70 Etymotic Mc5 and $150 Klipsch Image X10. In general, this is true of most IEMs, or In Ear Monitors, also called Earphones, and sometimes mistaken for Earbuds. IEMs are characterized by their narrower profile when compared to earbuds, though you can see from the picture above that the sizes differ greatly. The Klipsh Image X10 is the smallest copper one in the middle, and the Ultimate Ears TripleFi 10 is the largest, followed closely by the Skullcandy, which is similar in size to most popilar IEMs:

What makes an IEM isolate is the fact that material is coming between your eardrum and the outside world, whereas noise isolation is based on a chip in the headphone detecting sound and creating an inverse sound that is played through the headphone speaker to counteract the incoming sound. Ports on either headphones or IEMs will diminish this as sound will get through, and that is why the black and narrow Klipsch S2 does not isolate as well (because there is a small port on it underneath.) If you want to make your own charts, check out this resource:

http://www.headphone.com/learning-center/build-a-graph.php

Lastly, comfort is determined by the eartip, which can come in several shapes, materials and sizes. Personally, I find that foam stays in better than silicon, and that the more flanges you can fit in your ear, the harder it will be to pull them out. As for comfort, most eartips are round, a circle at the end. With Klipsch eartips though, they are oval, and don't press on your ear canal as much. This, combined with a small sized housing in the earphone means that neither the tip, the nozzle, nor the body of the earphone presses too much against the inside of your ear. For a general look at the size of eartips that come with the mentioned earphones, look at the picture below:

The Triple flange ones with the mushroom and large foam come with the Etymotics, and the oval shaped ones and double flange come with the Klipsch. In order of comfort greatest to least with these I'd say it's the Klipsch Ovals>Etymotic Mushroom>Silicon Round>Large Foam>Double Flange>Triple Flange. Some others that I have are the Monster Supertips, and they are quite comfortable as well, and the foam ones have a coating so that they won't get earwax impregnated in them. If it comes down to not thinking there are eartips that will be comfortable, believe me, they are out there, and since the $200 budget is well over the $150 the Klipsch Image X10 costs, there is a lot of money left over for trying different eartips if you don't find the Klipsch ones to be the best.

May I ask how do Sennheiser CX 400 II and CX 870 perform, mostly from the noise cancelling point of view?

IEMs will offer best noise isolation, but may not be comfortable for everyone. I know I can't stand IEMs no matter what size or position....sounds kinda weird.

If you want portable headphones that isolate well and don't stick in your ears. Sennheiser HD 25-1 II are $200 are highly reccomended as the best non-IEM portable.