I’ll update this post as time allows. For now, you’ll find a lot of scripts in the public domain the Gutenberg Project web site. These can be read on line or downloaded—or you can copy the text to an editable document and format it to save ink and paper.
124 random plays in PDF from Aeschylus to John Van Druten under Drama at Fadedpages.com .
Select from a list of 441 works of classical literature (poetry, prose, and drama) by 59 different authors at MIT’s Internet Classics Archives.
249 plays at Read Print (join to download).