There's a small but real market for this sort of thing. If you want to sell it to a publisher, as opposed to self-publishing through Lulu or whatever (and there's no shame in that; self-publishing, as opposed to vanity publishing, is perfectly respectable, though it won't turn a profit if you don't know how to deal with the business end), these are the things the agent who sells you to the publisher will want to know:
What is your expertise in this field?
What would make this work different from other, similar works on the market? (Do you, for instance, have access to primary sources that have not been used before? Do you have personal experience to draw on, or a profession that gives your opinions extra weight? Does your website act as a clearinghouse for reports, do you run a cryptozoological museum, and so on and so forth.)
Do you have previous publication credits, and what sort? Blogs and self-publications that did not achieve a noticeable amount of market notice won't count here; nonfiction credits in another field will at least demonstrate your ability to complete a project; your Ph.D. thesis is better noted as expertise.
Do not attempt to sell this work, even if it's already written, until you have good answers to those questions!
The thing to ask yourself here, now, is: Do I want to write this thing, or do I think it would be cool to have written it?
If the first - sit down and start writing now, today. Yes, yes, I know you don't have your material together, but writing a list of goals you want to accomplish or topics you want to cover counts, as does trying out different formats (Narrative? Encyclopedia? Chapters of hard information with sidebars or interludes of anecdotal material? So many possibilities!), as does outlining what you already feel competent to write and noting where research should be focused first. Start writing every day and the momentum will carry you forward. Many viable books have never seen the light of day because the author never put his butt in the chair and started writing.
If the second - put it on the shelf next to the other things you'd like to have done, like gourmet cooking school, climbing Everest, sailing round the world, and living in a castle with a romance cover model. This sort of thing is too much work to do if you don't enjoy the process, especially given the uncertainty and potential tininess of the financial reward.
You don't need our approval for this. You need to want it. Everything else can be made to fall into place if you want it effectively enough.
I thought it would be cool if it would get published, so i'd be interested in seeing where you go with this Lauren