If I read that auction I would assume it was even worse and he was attempting to lease me the domain name at $15 per year.

That being said, you might be able to convince ebay he is trying to avoid paying ebay final value fees on that $15. Either way, your choices are pretty much limited to reporting him and leaving feedback.

Unless he is selling so many sites that the negative is quickly pushed off the first page,
I disagree that negative feedback won't hurt him. There are so many crappy sites for sale on ebay, there's no reason to buy one from someone with bad feedback. I'm not saying you'll shut down his business, but his average sale will definitely decline for as long as that negative is on the first page of his feedback profile.