I've got two problems, a bad 80gb Harddrive and a lack of funds to replace it. The question is, can I replace the 80gb drive with a 30gb drive and not have to deal with the battery like you do in an upgrade? Or would I be forced to downgrade the battery as well? Thank you very much! (I know I'll have to deal with the smaller drive leaving free space in the ipod, I have that covered.)

Welcome to iLounge.

You will most likely need to replace the battery as well so it's for the 30GB model. These shouldn't cost more than a few dollars on eBay. If you want, you can always try using the original battery in there. I think the main reason why it should be replaced is because it's fit for the 60GB/80GB models. Since you are finding a workaround for the smaller drive leaving space around (unless you replace the back plate), you might want to test it out and see how it works. If anything, it's just a longer battery cable providing more power.

Yes, you can leave the battery as long as you put the original back case back on. The 60/80 GB battery is larger than the 30 GB battery because the 30 has the thinner back case. But it is the same voltage and goes in the same location in the case relative to the hard drive. The only issue you will have is the extra space because of the thinner drive, as you already mentioned. Good luck.