The iPod's battery is replaceable. About fifty bucks for a new one.
Make that $200+ to replace the hard-wired battery which can only be surgically removed (unless they redesigned the ipod since last Christmas). There are I HATE IPODS websites out there - look them up. The Creative Nomad battery is really replaceable - the top pops open and you can go to Best Buy and get a new one (or pay twice as much for half the disk space and get yourself an ipod comrade and if you have any WMV files you are SOL)