You can get USGS (United States Geologic Survey) maps here
http://www.usgs.gov/pubprod/You can download them and print them at home but they will be the wrong size... i.e. the paper is too small to fit the map onto.
You can go to Kinko's and get them to print them on the right sized paper... but that is expensive.
You can go to your local University's Library and get them to make you a copy of any of the maps that they have in their map room... This is the option I go with most of the time. It cost me $4 to get a black and white topo on regular paper... Sure it wears out pretty quick but that is what I am buying a throw away map.
The USGS will print you full size/full colour maps for $7 each if I recall correctly, don't contact your local branch. Use the website.
I think that the best option by far for something that you are going to keep in your kit is to get one of those Nat Geo map printers at REI to print you a map, they use this awesome plastic as paper and that shit is way better than any laminated crap I've ever seen. You can cut the map and its still waterproof. It is really a good option and you can get your map how ever you like it.. The usgs map doesn't show enough area? no problem. You live on the edge of the usgs map? no problem. You need to pour gas into something and don't have a funnel? no problem. These are the best maps I have ever used and worth the money at twice the price.