My editing specialty is non-fiction, my editing niche straddles the line between developmental editing and line editing (often either/or), and my editing mantra remains, "Consider the reader!"
After an initial gratis consultation, usually by phone, of up to one hour, I charge $170 an hour, which includes on line edits and suggestions, as well as an overall written precis. I suggest that new clients pay for an initial five or ten hours, whichever is comfortable, then decide at specific intervals to continue or not. (Virtually all do continue to the end of the draft, but that is entirely the client's decision.)
More on my editing approach at alisonowings.com, click on Editing. Referrrals gladly provided.