If your material has a long life, you could self publish. Then a year or 2 later after sales have dwindled you could look for a publisher interested in taking over it & giving it a new life.

If you self publish you can contract your own professional editor or reviewers. It's worth doing if you're spending significant time/money in the book &/or marketing. Some popular tech book publishers crowdsource their editing by giving free copies to people interested in editing.