they are being reproed. lot of sellers... PG Classics, Classic industries, YR1, Firestone Collectibles, Hoover restorations, Dalescudashop, BEAparts, Laysons... those are the first coming to my mind.
- - - Updated - - -
sorry, I noticed you were asking just for the glass.
Believe it or not, I got one LONG time ago, and I think got it from rockauto!!
Check a local glass company they maybe able to make it for you.