The answer to this question is: It depends.
At the presentation I attended on Saturday, thriller writer Rick Pullen talked at some length about the editing process, developmental editors, copy editors, and line editors. He shared his trials (and money spent) in finding just the right person for his particular work. He also has his daughters, wife, and ex-girlfriend reading and advising on his manuscript.
It was almost like my Sisters-in-Crime were listening in on that presentation, because this week the SinC Self-Published Authors Yahoo! Group was abuzz with questions/opinions/answers on whether or not one should hire a professional editor, and how much should one pay for those services. The consensus so far was anything from $300 to $1,500, but then, again, we get that word “depends.” And some made the point – you get what you pay for.
It also depends on which kind of editor you want. They each have a different job and should be done in the appropriate order. Before hiring an editor, do your homework. Know exactly what services each editor performs and decide what kind of editing you need.
To decide whether you need to hire professional help, ask these questions: How good are you at typing, spelling, grammar, style, punctuation, formatting, pacing? How good are your editing skills? Can you find those typos, like “sigh,” when you meant “sign?” Can your eyes pick up extra words or missing words – you know, every author has them. It happens when you are cutting, pasting, moving text around. Can you pick out repeated sentence starts and sentences that are too long? If the answer is yes to most of the above, then you probably don’t need to hire an editor. But you still need experienced proofreaders. There is no way any writer can pick up on all those issues.
Besides having experienced proofreaders, I am also utilizing the Prowritingaid.com website to run my chapters through. That software points out where I might have issues. I say, “might have,” because you, the writer, have the final say. It’s software, after all, not human interaction. I found that some issues the software pointed out where not issues at all. But for the most part, it has helped me tremendously in pointing out overused words, long sentences, grammar and style. It allowed me to send a much cleaner manuscript to my First Readers.