Where to order custom glass or acrylic?

I want a 19.3" x 19.3" piece of acrylic or glass with a big rectangle cut in the middle of it around 4 inches wide and 12 inches long.

I went to a local glass cutter and they totally failed and then forgot about the project. Is there someone online I can use who is more reliable? I can make up some quick plans in Illustrator.

 

I'd try other local glass shops if possible (if you have a local reef club they might have recommendations).

From what I was looking at, it seemed like the online options were more expensive (at least compared to what I found locally where I am)... and then you have to worry about shipping.