We hear that you are all looking for a play with at least three acts and realize that local collections are limited. Try this link (Project Gutenberg) and go to under 'search book catalog' type in the word 'play' or the words 'play in three acts'.
For a more specialized search, go to catalog and do a title word(s) search for 'play'. Or go to their advanced search and use 'play' as the subject and 'English' as the language. I got quite a long list of results to choose from. The eBooks on Project Gutenberg are free downloads too!
You can also search for specific authors or titles.
Here's a few quick links to some of their three act plays:
A Doll's House by Henrik Isben
Pygmalion by Bernard Shaw
Candida by Bernard Shaw
Mary Stuart by Friedrich Schiller
Wilhelm Tell by Fredrich Schiller
The School for Husbands by Moliere
The Importance of Being Earnest by Oscar Wilde
The Thirteenth Chair by Bayard Veiller
The Faith Healer by William Vaughn Moody
The Black Cat by John Todhunter
The Surrender of Calais by George Colman