Someday I'll have a bunch of 18th and 19th century costumes made up for me. I was always stunned by the photos of the Wyeth family romping about in seemingly accurate Revolutionary War era costumes. I honestly don't know how people get access to these things. Some time ago, my brother-in-law took me to visit his friend Jim Brothers' sculpture studio in Kansas. His work for the D-Day Museum and monument in Normandy, allowed him access to piles of vintage WWII equipment. I drooled.
I have access to what a badly dressed male would've worn in the 1990's and bits and pieces of Boy Scout uniforms from the 1970's. It's a start, I guess!