I would NEVER actually "buy" glass. Every single home in North America is or has been switched from aluminum framed to vinyl frames. They don't re-use the glass, they junk it. But they need to re-claim the aluminum, because its rare and expensive now. Go to a vinyl window shop that replaces peoples home windows and you'll find a TON of free glass. I have literally TONS of the stuff. Every single thickness and grade you could think of.