oh, well first off the ksc's aren't earbuds. the 50s are clip ons and the 55s have one of those behind the headbands. the senn px100s are closed with an over the headband.
the senn mx series tends to be the only earbuds people regard as being worth spending money on. that doesn't mean they're good, just that they're tolerable. the mx500s go for about 20 bucks, give or take. for the most part though all earbuds sound like shit. if you really want earbuds and want the best sounding earbuds you can get for a reasonable price though, the mx500s are a pretty good bet. some people also like the sony ex71 (pseudo in-ear) which i think run about 30 something.
right now i'm using the mx series-sound-alikes that come with the iriver for portables, but this is mostly because i can't afford a pair of canalphones and i have senn HD600s (200+$) at home.
if you ask me, 15$ is nothing to spend on a pair of half-decent headphones if your alternative is using freebie bullshit. i'm not so sure about spending 15$ on a pair of earbuds though. you should look into the ksc's and px100s though. those are definitely worth a few bucks more.
