Getty Images has a new program that lets you use some of their large supply of professional images for free for nonprofit purposes. It's called their "Embed Images" service. It's less flexible than you might want. You can scale the image, but apparently can't crop it. You have to use their embedded viewer. (They give you an "iframe" to insert in your HTML.)
Still, there are possibilities.
Can I embed in a blog post? Let's give it a try: