Hi Jim,
I think that Steve pretty well hit the nail on the head.
You have two choices, self-publish, or present your project to a publisher.
If you present your project to a publisher (at what sounds like a late stage in your case), they are going to evaluate the project that you outline to them, and then tell you how many pages it will be, how many (if any) foldouts there will be, and how much color there will be, and also the type of binding. They will also set the price.
In turn, they will assume the bulk of the risk, and pay you for your efforts (if a publisher wants you to pay them - this is a red flag). Typically this will be in the form of an advance against royalty. If the book sells well, and has legs (and IF the publisher stays in business), this can work out well. If you go that route, be sure that the contract includes language the reverts the rights to you in various circumstances, such as bankruptcy of the publisher.
If you opt to go the self-publish route, the choices are print on demand or conventional printing - the latter giving better quality in my opinion. Conventional printing also requires more capital, as you will be buying an entire print run. Keep in mind that with conventional printing , printing the first copy is VERY expensive, each copy after that you are paying basically for press time, paper and ink, thus the incremental cost is low. But again, that first copy is VERY expensive (think thousands of dollars).
Next will be deciding domestic or offshore printer. Colors tend to be more vibrant offshore (lax environmental laws), and unit cost lower - but there are is freight, customs, brokerage, taxes, etc., that have to be factored in - plus big uncertainties on delivery time, and little recourse in the event something goes off the skids.
All of this being said, the largest hurdle in self-publishing (either conventional or print on demand) is distribution. You can forget seeing your book in Barnes and Noble, and selling via Amazon has its own set of hurdles. Seeing your work in hobby shops is unlikely - and even the ship's stores will be a challenge as those are typically operated by an outside contractor (Event Network), who has little interest in books.
Steve can probably speak to the hurdles of distribution with more authority than I - but from my seat, you need to plan on your sales being only those books you personally can sell.
From my personal experience, between 50 and 75% of the people who say "I will buy your book" actually will - but a whole host of people will pop up asking you to donate books to various and sundry shows and charities, and it is worthwhile to supply some of these, as well as review copies, and there is a cost that is associated with all of this, and that cost must be borne by the books that you DO sell.
Hope some of this is helpful.

Best,
David Doyle
www.DavidDoyleBooks.com