Ear Canal Headphones are one of the newer models in the headphones market and can run a pretty steep price ranging from $100-$900 for a pair.
There are many benefits that come from having ear canal headphones.
Canal phones are headphones that fit snugly in your ear canal and feel much like ear plugs. They're designed to fit so snugly that they block out most external ambient noise which does a lot of good things for your listening experience. You don't have to have the volume up nearly as loud to get the quality of sound you need which prolongs battery times. They're small so you don't have to lug big noise canceling headphones all over the place.
There are some draw back to Ear canal phones also known as canalphones. They block out external noise so well its very difficult if not impossible to have conversations with people while your headphones are in. These can also be dangerous if you wan to use them for exercise since you lack of external ambient noise will cause you to be unaware of possible threats like oncoming cars and .. well you know stalkers and stuff :)
Who should get canal-phones? It really depends on what you're going for. Because of their expense these will most likely appeal to more refined, picky listeners while. Those you savor free loss-less audio and who cringe at the thought 128kbps coming from a cheap portable CD player.
Many people complain about a loss of the lower frequencies with ear canal headphones. This is usually because of quality of the seal in your ear canal. If the seal is better and tighter then the lower frequencies wont be able to sneak out so easily. This is why many companies offer different sizes foam tips because just like anything else on us weird humans our body parts are all different some people have bigger ear canals than others. So if you find that the you lose a lot of your base you should change out the foam tip for something larger that will fill your ear better.