There is a difference between printing and print on demand companies. It's important to know this before deciding how you want to get your book into print. After reading this page, compare the facts to those presented on my print on demand page.
     A printing company does nothing more than print your pages and bind them together inside a cover. Since I haven't used a regular printer, I don't know what type of files you have to provide. Once the printer loads your files onto a computer, they then set up the plates necessary for the press. Ink is added to the press rollers. Once the set up is complete, they press operator prints out a particular number of copies of the book. The pages are then trimmed to the proper size and bound inside the cover.
     This is a generalization of the process, but should give you an idea how a book gets printed. Due to the time and material needed to complete the process, the author is required to purchase a minimum number of books at the cost set by the company. Most often the cost per book is will decrease as the number of copies ordered increases, although each company has their own pricing policies. When comparing prices, don't sacrifice professional quality work in exchange for a lower overall price.
     Once you have a printed and bound book, the real work begins. The printer isn't going to do anything to sell your book. Unless you want a box filled with 100 or more books sitting in your closet, you have to go out and sell them. Whether you choose to sell the books at such places as your own website or at flea markets, you have to let people know where the book can be purchased. The only way to do that is to advertise and talk to people.
     When your "warehouse" is empty or near empty, you have to go back to the printing company and order more copies. Again, they're probably going to require you to purchase a minimum number of copies. As you probably already figured out, whatever books you don't sell are going to stay in a box in your closet. Unless you can personally sell enough books from the original number of copies you ordered or those you buy later because you need more stock, the amount you pay to have the book printed will never be recovered.
     If you'll be happy just to say you've published and sold a book, this might be the way to go. The drawbacks to using a printing company are the initial cost to have the book printed, having to sell the book yourself, and having all of those extra books sitting around if you run out of customers.
     Important: Never sign on with a company if they insist that you sign over the copyright of your work to them.