Koss PortaPro
Here: $30
This is an open type headphone, and as such offers no isolation, however it has a huge sound-stage that seems to place the music around your head, rather than in it like a closed back headphone. Koss provides a lifetime no questions asked warranty, and these are very durable.
If you have never heard an open headphone before, the experience is simply amazing. Other strong points on this 'phone are it bass, especially with drums, nothing else at this price point offers this level of bass and its very light durable construction. I have listned to and owned other 'phones costing upwards of $150 and still find myself taking time to listen to my PortaPro.