another place I like, but I don't shop in that price range when I get headphones is
HeadRoom - Right Between Your Ears. I think it's a good site. It's a bunch of audiophile guys who run the site, and give a good analysis on different headphones.
Personally, I like the Etymotic ear canal headphones. The ones I got are still $200.
Looking at their site, the cheap ear-canal cans are $50. For the price you're still getting nice cans, that are natural noise canceling, and thus you don't need to turn up the volume as load compared to ear-bud cans like those come with the iPod.
Here is a link to the ear-canal offerings:
linky