There's one place,
www.jmcorp.com that sells audio stuff just for bikes, but they did not offer what you're looking for when I got my replacement speakers. They might now; I'd check 'em out. Real cool people, too. And my speakers are great, no hassle dealing with them, so I'm not shy to recomend them. Good luck... whatever you go with, let me know, my wife needs a stereo for the heritage. Like you, she doesn't want the fairing.