Many researchers at the moment happily pay APCs (=Open Access article processing charges) in the several thousands of dollars — this is way more than is required as a minimal cost of editing. In fact, you can easily hire a freelance editor to work on your paper for less. If the process becomes minimally streamlined it could be made very affordable: at the moment, a lot of the work of a journal editor is (intentionally, as well as due to inertia) due to the utter lack of streamlining.