Ipod touch reaching the end of its life.?

I've had my Ipod touch 1st generation since December 2007 and the battery is finally pretty much dead., how much is it for apples battery replacement service? is it worth it ? what does it actually include? or should buy myself a new mp3 player? and if so, should it be a new ipod touch? or what... what do you think as im indecisive