Many potential clients are taken aback by what it costs to hire an editor. I think few realize that it's actually a craft and skill that people have to learn. Editors have degrees, and have studied and gone to school, and have gained their experience through years of training and studying the things that need to be studied to whip prose and text into shape. I myself have a degree in English and a post-grad certificate in Book and Magazine Publishing along with 11 years of real-world experience. We aren't lawyers, so we don't charge $400 an hour, but asking for $40-80 per hour is not unreasonable. What do you pay your hairdresser, your masseuse, graphic designer, plumber? That rate and more.
So to those who have no idea what to expect to pay an editor, let me give you some info you can digest before approaching an editor, spending an hour discussing the project, and having that editor prepare a quote (which also takes time), only to discover that in fact you are put off by how much it costs and won't pursue the relationship any further. Consider this your research and save us all some time.
Most editors can copy edit 1000-1500 words per hour, which is 4-6 pages per hour. (Generally, this number is lower with substantive edits and can be doubled for proofreads.)
Yes, that's right: 4-6 pages per hour.
Now, say you have a 100,000 word manuscript. Divide 100,000 by 1500. That's the number of hours it will take to edit your manuscript. In this case, it's 66 hours.
Most people have no idea that editing a book can take that long, but it does and many times even longer.
Multiply your hours by the average per hour rate and you have your fee. If an editor bills out at $40 per hour, expect to pay $2640. Not unreasonable to turn your project into crisp, clean shape. You have to think of it in terms of value: what value does this bring me? Obviously, for example, if it's a self-published work, the value could be quite a bit if you sell a lot of books.