If you're not hell-bent on storing gigs and gigs of MP3s on your MP3 player, you might consider the Creative MuVo TX FM. It's about the size of 3 AAA batteries laid side-by-side. It's like a USB pen drive, so you just plug it into your computer, drag-n-drop your MP3/WMA's, then plug the battery in and go. I got my 256M model for under $100.
http://us.creative.com/products/prod...0&product=9672