You could rummage forever through piles of cheap headphones, and even worse find that a dissapointing %95 of those headphones are just that - cheap. The sound is mediocre, probably on par with stock earbuds. Every once in a while, however, a gem comes along. This, my friends, is the Koss KSC75 ($11.00 at amazon) clip-on heaphone.
The KSC75 looks cheap, but it stops there. These suckers can rock! They deliver a full sound, surprising for the size and price. They absolutely destroy the Apple earbuds. The bass is impressive, and commendably tight. The midrange has real body to it. And the highs sound pleasing too. They also improve with a headphone amp, so they even have a little room to grow. I seriously doubt that anything short of $50+ will beat these phones. The have a Grado-like sound, and assuming you aren't the most sound-critical listener, i doubt the average head-bopper will notice any difference. The downside is, like the Grados, they leak out sound - not as much, but still a noticeable amount.
The bottom line is these things are absolutely amazing for the price, buy a couple pairs while they're still cheap on amazon or your local radioshack, there have been some rumours of the KSC75s being disconntinued..NO!
DIY Easy Quarter Mod: Increase the highs of this headphone, many people say this considerably increases the sound quality. Remove the pads, place a quarter in the centre of each one. Grab an exacto-knife (careful!) and cut around the quarter. You now have a quarter-sized hole in the pads, put them back on, and you will see some of the driver screen exposed. Have a listen, they sound even better, in my humble opinion of course!