I always hesitate to recommend or bash particular headphones/earbuds/speakers as universally appropriate for other people because both individual preferences and styles of music make a big difference in what one finds good or acceptable. But having said that, I'll mention several options that have worked well for me in the "not cheap but not a car payment" price categories.
The powered speakers TubeMonkey mentions above are apparently sold by a variety of vendors at various price points. I have a pair similar to the ones he/she describes from iHome. Less expensive versions with the same overall design are available but I can't vouch for their quality. The ones I have are really great (imo.)
http://www.amazon.com/IHOME-iHM79BC-...0526360&sr=8-2
As far as headphones are concerned, the Sennheiser P-100ii "foldable" headphones are truly superb for the money (according to me and to many other reviewers.) If you're looking for chest rattling bass they're not for you. But if you want accurate sound reproduction, very light weight, and easy portability, they're superb. They fold into a package about the size of a pair of eyeglasses and you can wear them for hours without strain.
In addition, Sennheiser stands behind their products. Broke an earlier version of these after three years (literally sat on them) and Sennheiser sent me a replacement free of charge.
http://www.amazon.com/Sennheiser-PX-...0526647&sr=1-2
I hate earbuds. They simply don't work for my (apparently) weird shaped ear canals. Instead I prefer in-ear noise isolating earphones when I fly. Shure makes some of the best in the industry. Multiple tips make fitting to your ear a cinch and you won't have to worry about the terror before the plane crashes. You'll never hear the pilot telling you it's going to happen. The sound is marvelous and feels like it's inside your head.
In addition, because the cables are replaceable you won't have to replace the earphones if the connection wears out.
http://www.amazon.com/Shure-SE215-K-...0526995&sr=1-2