People do have this mod. I'm not saying that people don't do it, I just have strong opinions about it..

The seal kit comes from the dealer, and the acrylic (Plexiglass) or polycarbonate (Lexan) comes from someplace like FAL. Yes, the same FAL that makes fans. I don't really know if they make back glass or not, they make side windows and stuff like that... There are other companies too, hatch glass isn't that easy to find sometimes..