I just bought a used hardtop. The rear glass was missing. Who sells them? They have holes through the glass for the top supports and the lift mechanism. So I would expect this glass would be a hard top find thing.
If you have the hardware, your in there. If not, its hard to find one. But if you need glass, shop around. I called a couple local shops, and i think, if I remember right it was under two hundred for glass.