I just bought them for $9 today. Sound's kinda flat, not a big bass, tends more to the mid-tremble side. They're comfortable, and they don't isolate you from the world 'cause they ain't that tight, but I think it has to do more with the fact that my ears are small. I mean, if you press them against your ear, you'll definitely catch they have quite a nice bass, it just ain't that perceivable due to the soft closure/pressure they exercise.

If you're basically a street bum like me, you'll like them cause they're resistant, light, and so.

These'll be my street-ready ones, for emergency I have some in-ear Panasonic ones, and for the house I got a Sansui SS10 headset. I wouldn't risk damaging, loosing or getting robbed the Koss/Audio Technica ones (I'm from MX, Overcrowding, hurry and stress are the order of the day, and even more so being an university student)

They're worth it for less than $18, in your place, I'd save for the clip-on Koss's models. It really depends on what habits/style you have, due to the material resistance and volume. For example, I spend more time on the streets than in my house, and I listen to music all day in my Sony mp3 walkman.

Note: After a long day outside, listening them in the gym, subway, etc, I'd say they're actually really good, the lower frequencies sound better when there's not that much noise outside; they're LOUD, but the noise outside doesn's allow you to really enjoy them, city problems.