First stop look at local library, (Disney's US Presidents). The library has a lot of free resources. Also Half Price books has a lot of bargain deals for dvds.
Other Resources include:
Learn Our History by Mike Huckabee (if you watch he will send out offers for FREE just pay S/H).
Drive Thru History (This is on NetFlix right now (limited time), Liberty'sKids, Howard Zinn's A People's History of the USA (has a documentary made), History Channels: The Story of Us & How the States Got Their Shapes, Sonlight for High School American History, Monumental, Alexander Hamilton History, National Geographic's Lewis and Clark, Ken Burns (especially the Civil War), the History Channel's War of 1812, Frontier House by PBS.
For older kids, Liberty: The American Revolution with caution there is a mention of rape in the section about the Battle of LI.
Learn Our History & American Heritage Series.