I'm sure you've bought your mp3 player already, but this may be helpful to somebody else browsing the forum...
I'm not sure about the battery on my mp3 player, but I have a Samsung that I love. I bought it at Best Buy for less than $100, and it looks like a money clip. It clips on my shirt sleeve, and it is so small and lightweight that it doesn't flop around while I exercise. I love it, and if it ever wears out, I'll buy another one just like it. It is about 2.5 inches long, about 1/2 inch thick, and very light. No bells and whistles like movies and color screens, but I don't need it. And the sound is good, too. I can't remember who made my first one - I think it was Creative Labs, and there was no bass, and the sound quality wasn't good. No problems at all with my Samsung.
The batteries are not removable, but it does recharge on my computer, and hopefully it has a rechargeable battery that I can replace. I'm thinking it does, because I was also turned off by the iPod battery situation and I wanted something more permanent. I actually thought the iPod was replaceable, but only by them. I had it in my head that the thing gets mailed off, battery replaced, and returned - and I didn't want to do without my mp3 player for a week waiting on a battery.
