I've gone through soooooooo many earbuds searching for the perfect pair. They never seem to fit right and the bass always suffers. I've tried $200 shures, $50 sonys, and $150 Bose. In the end, I have discovered that nothing compares to the comfortable fit, decent sound, awesome style, and great value of the stock Apple earbuds. If you buy some foam covers to put over them, they fit very well and sound great. I think they are worth way more than the $30 Apple charges. But that's just me.... Earbuds are a very personal thing and one may not work well for everyone.
As a sidenote, I have heard great things about those UltimateEars