Lulu is a self-publishing service, run like a business, without checking for quality. They make money, and you won't sell very many copies (around a hundred, IIRC).
There are publishing houses which will pay you an advance (a couple thousand), and then, after that advance is eaten up, will pay you a cut of the profits. They do check for quality. For a first book, you'd write it on spec (write the whole thing by yourself first) and then start submitting it (at least for fiction... I don't know much about nonfiction) to said publishing houses. Or it's possible to get a contract ahead of time. Apparently you really need an agent before you sign anything, but a good agent takes a percentage of your earnings, so if the deal falls through it doesn't cost you anything. (A bad agent charges up-front and then lets the deal fall through.)
It depends on whether it's of enough general interest for one of the latter sort to pick it up or not. If not, self-publish. Lulu's one such service, as is CreateSpace.
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I'm using a non-verbal right now. I wish you could see it. --dyingofpoetry
NOT A DOCTOR