You can also hire a good technical editor and do not necessarily need to go through a publisher to have that "second set of eyes". Or even use a college English major.

Using a major publisher, even if you could get them to look at your book, does not guarentee quality either. I was really disappointed in the printing and paper quality of the latest edition of "Sierra Peaks and Passes" published by the Seattle Mountaineers. And quality with respect to wording is not necessarily quality with respect to what you are trying to convey. For example, the Falcon series of guidebooks are very formula driven - OK if that is the formula you want for your work, but I personally do not like the format.

You can also hire a layout person and a technical editor independent of a publisher, if you can afford it. Otherwise, at a minimum you need a friend who knows the material but is not an expert to read the book to see that it is easily understood. I find that what I know too well, I unintentionally skip important information. There are also people out there who will "ghost write" your book.

Self publishing is economical in up-front investment, but you have to do the majority of the promoting. It depends on your goals. Lots of people simply want the creative outlet and accomplishment of writing a book. It is great that you can put your ideas in a public forum without others telling you how to do it - but that does not mean that others will also like your format! And if you self-edit there will be mistakes. Only you can decide if potential errors would detract enough to keep people from buying your "ideas". For me personally, if the information is solid and what I want, I will tolerate a bit of butchering of the King's English.