I assume you’re talking about
self-publishing.
With the normal approach, the costs are borne by the publisher: (1) you submit a manuscript (or, if you’re already a known quantity, a proposal): (2) the publisher decides it likes it and accepts it; (3) the publisher offers you an advance against any profits and gets on with the job (and so do you, if it’s only a proposal and you have yet to write the thing).
Step (2) is the big roadblock. Probably ninety-nine out of a hundred books get rejected by publishers, especially if they come in “over the transom” – unsolicited.
That leaves basically three methods: the vanity press, publishing-on-demand, and true self-publishing.
Vanity presses such as
Vantage will take whatever you want them to print, charge you for the privilege, do a small print run (or however large a one you’re willing to pay for) and a tiny bit of advertising. They’re not going to send out the books for review or try to place them in bookstores. You’ll pay quite a bit for the pleasure of being a “published author”.
There are now companies like
XLibris that offer publish-on-demand facilities. What you get this way can be as cheap or as expensive as you like, depending on the degree of involvement you want from the publisher. You can get them to work with you on jacket design, layout, merchandising – all these things run the price up. Or you can do most of it yourself to keep the price down. Since print is on demand, that can also serve to keep costs down.
Finally, there’s true self-publishing. Sometimes it starts small, as with
the Joy of Cooking by Rombauer and
The Elements of Style by Strunk and White.
Edward Tufte, a Yale professor who taught statistics and graphical design, mortgaged his house to finance the first edition of
The Visual Display of Quantitative Information, which he sold (and still sells) himself – no agents, no royalties – very profitably. It’s a beautiful, large book; printing it was undoubtedly costly, and if he hadn’t been as well-known as he was and it hadn’t gotten a rave review in
Scientific American, he might be a
homeless Yale professor.
I don't want to be discouraging. There are success stories out there, including
What Color is Your Parachute? But it's not an easy road.