Gosh, it’s been many years since I last did it. I don’t even know what good prices are, anymore. Some hobby stores will carry panes and art supply stores often will have some. If you have a nearby university with an art program, you might check if they have a craft shop; some of them have public pricing.

Bullseye carries all kinds of panes, and they were the source of glass for my university’s Glass art program.

Hope that helps!