Shure's line of <A HREF="http://news.zdnet.com/2100-1040_22-5518139.html?tag=zdnn.alert">in-ear headphones,</A> priced from $99 to a breathtaking $500, have become the top status symbol accessory for the iPod, drawing approval even from Apple itself, which sells the devices in its retail stores. Shure's "E" series of earphones are different from earbuds and headphones in that they're inserted into the ear canal, where they form a tight seal that blocks out most outside noise and makes music sound more clear and crisp.