A reader asks: "How much should I pay my publisher?"
The answer of course, is that a publisher pays you. A publisher buys from you the rights to publish your work in certain markets. These rights are clearly set out in the publication contract, and they're limited, unless the publisher buys ALL rights. (It's never a good idea to sell all rights in your work, unless it's work that you're doing for hire.)
Standard commercial publication takes time, and your book can be rejected by any number of publishing houses, so it's not for the faint-hearted. If you don't want to go through the agonies of standard publication, self-publishing is an option. You should consider self-publishing if you're writing nonfiction, and your book is a "niche" topic, in which major publishers aren't interested because of the tiny market.
Self-publishing means that you bear all the costs, and you get all the profits. :-) Note: many writers choose to e-publish, because they're writing for a small target market, and because they can manage the entire process.
Beware of vanity publishers. I'm not a fan of vanity publishing - a deal where you pay a "publisher" to print up copies of your opus. These companies are not publishers, they're printers with delusions of grandeur.
In this blog, I keep hammering the point that PUBLISHERS PAY YOU. It's never, ever the other way around.