The Art Institute of Chicago recently revamped its website and released a searchable database of high-resolution art. Even better, a lot of the art is in the public domain, meaning you can legally use it however you want, even for commercial purposes.
(Check the copyright notice on each artwork’s page.) You’ll notice that while you can zoom in on most of the artworks, only the public-domain art will include a full-resolution download link.
For anything in the public domain, like the Monet, you can download the largest version, send it to a service like Framebridge, and have your own framed art print. Well, art print-out. But a classy one.
You could also, theoretically, use the public-domain art in an ad. Imagine the possibilities.