In Boulder, CO this weekend, Carol and I happened upon a store called Art Source International. They specialize in prints and maps, but really in maps. They have about 25,000 in their online listing and will frame and ship, and in some cases provided high-resolution (OK, they're medium resolution, because 1600x1200 stopped being high resolution a few years ago) images of the maps. Ask for George, he knows what he's doing!