Epson Scanners range from $199.99 to $3229.99. Use to create high resolution digital surrogates for access and preservation at 600 DPI, 16-bit, Adobe RGB.
For an individual the cheapest models capable of scanning content up to 6400 dpi with a 17” x 22” in scan area.
For tightly bound books:
A Plustek OpticBook A300. This scanner has a book edge – allowing for a user to scan into the gutter of a bound book without flattening the book on the glass.
Scholars at Yale have been photographing historical documents (early American) around New England, and are using a Canon Rebel Ti3 camera with a tripod and a Kaiser copy stand. Any medium-priced DSLR camera (Canon, etc.) would work; no need to spend $4000-5000.
EOS DSLR Cameras - Canon has an API that allows remote firing of the cameras with advanced features, useful in professional scanning systems.
With some special hardware, along with some proper techniques, it's possible to make excellent digitizations of film and print originals using a digital camera.