Maybe a framing shop could handle this? The bevel is the tricky part, of course. Worth calling the Framing Mill or Mona Lisa to ask.
These guys, across from the Home Depot, made some custom large beveled mirrors for me. I'm sure they can do a pane.
http://njmirror.com/UI/Home.aspx
Hi all - need a single pane of beveled glass for an old French door -- about 8.5x12 inches. Even hard to find options online! Thanks. Pete