I've had the Etymotic ER-6s for a year now. I fly a lot, so they get a good workout. I tried the more expensive models, but sent them back - the ER-6s sounded just as good, IMHO, for less than $100 on line. The $300 plus buds might sound slightly better, but not enough to justify the price difference.
Of course, that's just my opinion - I could be wrong...