My iPod is looking pretty scratched, and the back is dented... Is there any place i can buy a replacement case?

I have never seen anything like that... if I were you I would have bought a case from iSkin or some other company. If it can be done it would definately void your warranty.

ive already replaced my HD, so my warranty is long gone.. i wish i wouldve invested in something like iskin... i kept meaning too but bow its too late

What I would suggest is to go on eBay and try to find a non-working iPod of similar size and the same generation. Swap the non-working iPod's case for your current scratched up on and BAM you've got a new looking case for a lot less then it would cost to buy a new iPod.

And make sure you have some sort of "skin" or case ready to go so the same thing doesn't happen all over again. It's worth the $19 investment. You can even find cheaper skins on eBay so while you're shopping for a busted iPod to harvest it's casing, pick up a skin.

Good luck.