I'm not sure we've got a glass/mirror shop here -- that doesn't ring any bells, although I haven't tried buying glass much before. Searching online doesn't find me much.

But even at Lowe's, glass is clearly cheaper than TAP. I might adjust my plans to match the 30x36 size they sell. I'll just have to learn some new stuff about putting it in. Since I'm building the frame from scratch, all the "How To Install" videos don't help me much. Could I use a dado for this? I might need to make something closer to a traditional window frame (which is a lot more work, of course).