The Panasonic RP-HC55s are a set of in-ear active noise cancellers and can be found for as low as $60, making them one of the least expensive active-cancellers. The noise cancellation is controlled by an in-line pendant that's shaped like a short, fat pen, complete with cap. You click a button on the top of the "cap" to toggle cancellation on and off. Unfortunately, you can't opt to listen to your music without cancellation activated. Fortunately, one AAA battery will let you listen to music continuously for 100 hours, which is an incredible battery life. 

One issue to be aware of, however, is that the active noise cancellation pendant is awkward. If you don't clip it to your shirt it'll wave around like a heavy necklace and gradually pull your ear buds out. We highly recommend walking around with these untethered before you decide to keep them. If you can always keep the pendant clipped to something, then the headphones are actually more comfortable than the average in-ear. If you can't, however, they're not a comfortable wear. 

Performance  (read the full lab performance results at HeadphoneInfo.com)
For in-ear headphones, Panasonic's RP-HC55s weren't bad. The active noise cancellation feature lets the RP-HC55s isolate better than the average set of headphones, although a good set of normal in-ears can still best it. While this speaks well of the still-maturing active cancellation technology, the feature ends up translating into more problems than it's worth. Active noise cancellation adds noise and distorts playback, so these headphones aren't for audiophiles. The subpar audio performance might not matter to commuters looking to listen to music on the bus, however, since the outside noise will render the above issues moot.  

Comparisons  (read more in-depth comparisons at HeadphoneInfo.com)
The RP-HC55s aren't the best headphones we've seen. They can be a bit uncomfortable if you can't anchor the control pendant to something and don't have amazing audio quality. Fortunately, these headphones are also relatively inexpensive. Also, if you don't mind the pendant as we did, it'll end up being an inexpensive and somewhatcomfortable option. While we didn't like the lack of an option to turn off active cancellation while still having access to playback, the impressive battery life partially makes up for it. While you should consider the RP-HC55s if you're on a budget or need an inexpensive set of in-ears, there are many other in-ears that can isolate better and have better audio quality to boot.