The point is, when it comes to literary works, any subject matter is game. I once bought a pink little paperback titled, How To Make Love To A Man. Seriously. I bought this book many years ago out of curiosity and maybe learn a thing or two. (ahem..) LOL!
What I am trying to say is, if there is anything you are passionate about and know plenty of, you could write a book about it and there would be buyers.
Other similar books available by the same author, Dian Hanson.