The number of true book manufacturers in the U.S. is relatively small. When you talk with people in the business, the same names will crop up over and over. You can find some of these listed at the Book Manufacturer's Institute Web site. If you are a member of a publishing organization, such as Publishers Marketing Association, check with other association members to see which printers they recommend.
It's important to note that even among book manufacturers there are specialists, and if you find the printer that specializes in printing books similar to yours, you'll find the printer with the best price for your project. This is generally a function of the equipment setup at the plant; some presses are designed to print books by the hundreds of thousands while others are optimized for shorter runs of 1,000 to 5,000 copies.
Much of our work is with small publishers printing relatively short runs. For these projects, we have found the following printers to be competitive and competent: