I've never used them, but I know that American Printing House for the Blind undertakes commercial work for blind audiences. Contact them toll-free at 1-800-223-1839, by fax at 502-899-2284, or by email at [email protected]. I know nothing about their pricing.
Someone with a Scodix printer can print clear Braille characters atop conventionally printed text, thus producing a book that is usable by both sight-impaired and conventional readers. Scodix could probably steer you to an appropriate customer of theirs.