chevs of the forties has it in clear, grey and green. They also carry the
rubber around the rear window. It's not going to be cheap wherever you get it, unless it's used, then you have clarity and possibly scratches to deal with. Place an ad in the swap meet section for used glass.
Here's one a little cheaper
metro parts market You can get
templates for the side widows if you have a local glass shop that can make the side glass for you.