ok...but if you don't have it explicitly stated on your site that the picture has been copyrighted and is your property, then how the hell is this guy supposed to know you don't want it stolen? I mean, for all he knows, you coulda stolen the pic off of someone else's site and they stole it from someone else. Especially if it's a really good picture, it coulda come from a site that gives instructions on how to duplicate it and, for all we know, that site might not care or might actually promote taking pics off.
Granted, I can understand that you'd be a bit agitated as you went to the trouble of taking the picture with a 1200 dollar digital camera and uploaded it in your own time only to have some schmuck come around, right click and save image it, but it happens. I may be wrong on many different levels, but it's kind of an accepted standard. It's like jaywalking...there's a hefty fine for jaywalkin. It's relatively harmless, but illegal nonetheless, but do cops hunt down and prosecute jaywalkers? Only when they want to ruin someone's day or an individual agitates them, but not on a regular basis.
As far as the epidemic of people yanking stuff off of the web, that's kind of inherent in the web. It was designed so anyone could view your information and documents and make copies and proliferate them. If this is really bothering you, I suggest you come up with some hard evidence that you indeed took the pictures(kinda like your book example, I woulda usps'd myself a copy via registered mail) and send him an email politely asking that he take down the picture or you'll have to take some kind of action against him. Then, put a few lockdowns on your website that encrypts the source code and prevents right-clicking(The average joe will prolly be unable to rip images off, anandtechers on the other hand....

) . If he doesn't... you could go for legal action, or you can be underhanded and tell the winner of the auction how to do this 2 dollar mod for the car. Heck, if you REALLY want to ruin this guys day, drop 2 bucks on the mesh, make another whatever it is, and send it to the winner of auction with a letter explaining what's goin on...prolly get the guy some negative feedback and he won't be able to duplicate the scam.
just my 2 cents.