Are you talking about in-ear headphones for a walkman? Well, the price itself is not a good indicator for quality but you cannot really compare those with "closed" headphones that cover your ears completely. It also depends on the sound source of course. For a portable player those should be fine. My analog soundcard output is OK but far too noisy, in contrast the onboard soundchip sounds like crap - no kidding. Therefore, I (ab)use my minidisc recorder in pass-through mode - my soundcard is cheap but has an optical SP-DIF output. The minidisc recorder has a much better DSP than the PC soundcard.

I think 100-200 EUR is a reasonable price for good headphones but you really have to compare and test a few models because they sell a lot of crap in the same range. For example, some may have much deeper bass than others but totally suck at high frequencies or vice-versa. One thing that is often underestimated is the wear comfort. I have one set that either causes headaches because it's too tight and puts pressure on your skull or otherwise (if adjusted) kills your earlaps by too much pressure. Well, I should have believed the reviews but the bass qualities blinded me.

Anyway, I switched back to the older set (same brand coincidentally) which I can wear literally all day without any discomfort - I hardly notice them. In any case, stay away from wireless headphones unless you're willing to pay 500-1000 bucks for a proper *digital* set.