The 2001 HBO film Boycott—covering the 1955-1956 Montgomery bus boycotts (which I’ve written about here)—is a DVD with a not-so-great title and not-so-great cover art, but with fine acting, good recreation, and a helpful summary of those important days. You can pick it up from Amazon for only $6.99. It’s worth watching.
A short trailer is the only thing I can find online: