Another one??? What the he!! happened to integrity?
Bill, just like Gina, I would tell this jerk to honor the auction AT HIS LOSS. Maybe he will learn a lesson about selling on eBay. Sorry, I have no sympathy for people who do not read the rules and/or overlook the simple stuff. If you have ever sold anything on eBay, there is a process you go though (unless you use TurboLister, Ebay's free offline auction editor) and it's VERY hard to miss the Buy It Now entry.....
I would most assuredly report him to eBay though, regardless of auction outcome. Take screenshots of the auction, keep all you email, and report the arsehole.