Next best thing you could do is figure out where your style is being used if you can, then file a DMCA complaint against the site for using your copyrighted work when they don't have permission. It's free and takes less than an hour to do. Most hosts will handle these within 48 hours of receiving them. I've even had hosts in Russia respond swiftly to DMCA notices. Of course they could just switch hosts and keep using it, but it'll be quite an intrusive annoyance to them, especially if you file another at their new host and keep at it. They'll likely get tired of having to deal with their site being suspended all the time.
To add to the thread, I've had my custom style ripped and sold on warez forums, and the guy doing it was from Vietnam (though there were two other individuals doing it as well, one from UK, and one from USA). Always thought it was humorous seeing him pissed off when other people would give his rip away for free (which they bought from him and then released, he'd demand the thread releasing it be deleted and such). Just can't believe he'd be upset when he stole the product in the first place and didn't have to spend more than an afternoon creating it, if that, when I spent months creating it, and on top of that all the images are hotlinked to my site (which has been to my advantage for numerous reasons) so the theme download is just an XML file. I've since come up with various methods of preventing and blocking anyone from ripping my work again.
People that steal your work suck; people that steal your work and then sell it really suck.