Rascal, to answer your question about who makes them, Widoweater mentions many of them.
I bought some Zwickey "No Mercy" left bevel heads for my ten yr old this year, and found them to be typical Zwickey steel. WITH SOME WORK with a quality file, I was able to clean up the edges, and get them scary sharp, and ready to hunt.
About two weeks ago, I got a package of left bevel "Bonehead" broadheads from Abowyer, and found their quality to far exceed the Zwickey "No Mercy" heads by a wide margin. I got these heads for free, because I was one of the winners of the contest here on Tradgang, about naming their new line of broadheads.
I believe the Abowyer heads cost more, but I was able to have them hunting sharp in only a couple of minutes, and the Zwickey heads require a bit of work to get the job done.
I am a long time Zwickey fan, but if I was in the market for a single bevel, I would look at some of the other brands first. JMHO.