SkullCandy - $9 -$10
We use in-ears on Sundays worship services, and among those on the backline, the SkullCandy actually has better low response than many of the others I've tried. In fact, I was in a studio session playing drums and the guitar was in the room with me and I could NOT hear the click with my cans on because of the amp bleeding in. So, I pull out the skull candy and boom... can hear the click. (I'm not a great drummer, so hearing the click actually exposed my weakness... ha! but I could hear it!)
I've tried the iPod in ears, Sony over-the-ear, Shure models, and the Skull Candy still wins. They come with 3 sizes of soft ear pieces, so you can get one that fits well. They work well for the $10. The company also sells more expensive models, but I like mine just fine.