There are a number of companies that offer book printing services. No, matter which book printer you select you'll want to keep the following in mind to reduce cost and get your book printed in the fastest manner possible.
You'll want to get your book printed in one of the standard sizes which tend to work well for how to reference or novels 5.25 X 8.25, 5.5 X 8.5, 6 X 9 or 8.5 X 11. These sizes are in inches. The standard weight for paper in a book is 50lb or 60lb. Some book printers may charge you more for 60lb vs. 50lb.
While book binding may be done in a number of different ways, you'll want to use perfect bound in most cases to ensure your book is retail ready. Retail ready means your book has the same overall look and feel as books printed by traditional book publishers. Your front and back cover may be a 10pt C1S with matte, lamination or uv coating. A matte coating tends to have a dull look and feel, while laminated or UV cover adds a shining to the book and protects the cover as well.
Before deciding on any one printer ask many questions. You'll find that different printers specialize in different aspects of the business and they will have varying pricing. Some people prefer to use a local printer while others don't care where the printer is located as long as the price is the lowest possible. It's been my experience that the price of getting books printed tend to fluctuate primarily as a result of the price of paper. Generally, when a book printer gives you a quote it will be for 30, 60 or 90 days and sometimes longer if you ask.
For a list of nearly 100 book printers you'll want to download How to Self-Publish for Profit.
While we've discussed a bit about book printing remember that you should also consider publishing your book as an ebook and audio book depending on the type of book you're writing.