I just want to share an experience. I downloaded an ear training app onto my work computer (don't tell anyone!). I had three sets of inexpensive buds lying around. They were mostly used for listening to my voice mails and only occasionally for music. I never really gave them much thought.
However, I was floored after using this app. I set the app to a steel string guitar. The first set of no name buds sounded so horrific I grabbed a pair a cheep Shures I had. The tone of the guitar was night and day between the two. So I grabbed a third pair and it had a completely different tone than the other two. I really would have never expected this huge of a difference. If I hadn't heard it with my own ears I wouldn't have ever believed it. It was as if I chose a different sounding guitar from the app every time....
Most ear buds that come with phones and music players only serve to make it possible for the user to use it privately and most aftermarket buds are only meant to be a cheap replacement. If you want something better, it's necessary to pay for good ones.
I have a set that were part of the package everyone got when we went to an open house for one of the distributors of AV equipment in the area and I only tried them because I wanted to listen to music while I cut my grass and was curious about the sound. I have a set of Koss PortaPro headphones, but the buds block more sound.
The ones I got were from Pioneer and IIRC, the list price was $29. I had some music in Windows Media Player and I'm not sure what went wrong when I saved the songs, but they sounded horrible. I then opened iTunes and it was a night & day difference. They aren't bad. Not great, but they were $29.
The thing to look at is the format of the music. If it's 128K (or less) MP3, don't expect ANYTHING to sound good.