A quality website is your professional face to the world, and fortunately it takes relatively little money and effort to put on a good face.
Marketing & publishing resource
People are much more likely to buy your book if they feel a connection with you and see you as an expert willing to share your knowledge. A blog is a perfect way to establish such a connection.
Although you can do considerable publicity and marketing yourself, a commercial firm can bring useful expertise to promoting your book.
The savvy use of print-on-demand technology can lead to successful self-publishing.
If you do not feel comfortable taking on the tasks of managing production of your book -- for example, hiring and supervising an editor, designer, indexer, printer, etc. -- consider using a book packager or consultant.
There are many cautions about using a subsidy publisher, but if carefully managed, they can be useful under some circumstances.
The design of your book's cover and text is critical to its perception by readers as a quality book. Such design, if done correctly, will require a significant investment, but it is a one-time cost that will pay off handsomely in terms of sales and your reputation as an author/publisher.
While POD is the best way to produce small quantities of a book, offset printing yields by far the greatest economy of scale and can produce a more professional-looking product.
Getting your book into the commercial pipeline requires understanding the machinery of the book trade.