It's free. Thanks to the internet, the catalog is available 24/7, with the option of requesting that books get held for me at my branch. It's got scripts, acting books, biographies of actors, an amazing archive of film, soundtracks and scores of musicals, and did I mention that it's free?
And, if your library (like San Francisco Public) is connected to the Link+ system, that means you're able to borrow from even more libraries than just your own. Link+ is a network of libraries that includes public libraries and college libraries all over the state of California, as well as UNLV (they've got a lot of scripts).
When I'm looking for something in the online catalog, if they don't have it in the SF Public library system, I'll see a button that says 'search link+' which then searches this larger network, and usually finds a copy of what I want. I make a request, and it gets sent to my branch of the library, usually in a week or so. There are some limits to getting DVDs and CDs from these other sources, but I've been surprised at what scripts and reference books I'm able to get from it.
So, before you go ordering from Amazon or Sam French online, check the library - you might be able to save a few bucks!!