I'm looking for a source (preferrably free...or at least cheap) for hi res maps that I can use in a video project. I need to animate a boat along a waterway for a few miles and would like to be able to follow the boat along the path fairly closely so the map needs to be pretty large/hi resolution. Does anyone have any good suggestions?

I know only of this site but it's not cheap:
[www.mapresources.com]

You may be able to find a public domain map here:
[commons.wikimedia.org]

My software:
Pro Maintenance Tools - Tools to keep Final Cut Studio, Final Cut Pro X, Avid Media Composer and Adobe Premiere Pro running smoothly and fix problems when they arise
Pro Media Tools - Edit QuickTime chapters and metadata, detect gamma shifts, edit markers, watch renders and more
More tools...

Yes i think mapresources.com is best for you. I am using this from long time you can also find the solution of your problem.