When I reach a designing block, I often take to the internet to scour through the vast resources it has to offer. I have learned that the internet is a marvelous tool for the historical costume designer, with large amounts of free scanned in collections!
Here is a link that has dozens of color fashion plates from the 19th century! Simply scroll through to find the desired fashion plate, click on the image and it will take you to a screen where you can view the image in amazing detail and focus. Enjoy!!