Gizmodo.com has a great article on why you cannot get a good pair of in-ear earbuds/in-ear monitors.
“The difference between $300 set of buds and a $400 pair is nowhere near the jump from $20 to $100. Even smaller is the difference in models between generations. The best value on the market might be a previous-gen version of Shure’s 500 series buds at a cut rate ($290), but if you can find $100 earbuds for 70 bucks, it’s even better.”
I have the first generation of the Shure earbuds, and they still work and sound way better than the ones that come with the iPod/iPhone. I’d love to upgrade at some point to a really nice set, like the Shure 500s.