I think you should be legally safe if you offer to sell your Ipod that is already fully loaded with music as a used a Ipod. It is no different then selling a CD player and CD's in the same bundle.
All you need to do is list your Ipod on ebay or craigslist. It is not illegal to buy 10 ipods and load each of them with the identical music files.
I have close to 16,000 songs loaded on my ipod and I too only deal with full albums from my favorite artists. I have full albums of grunge, punk, various heavy metal, rock, pop, rap, reggae, house, alternative and beats. If I didn't have the time or the means to all of that music I would easily pay say $500 to somebody for the shit that I have in my ipod and the ipod device.