How much do freelance editors usually charge for their services?

Question

To edit technical writing by an author who speaks/writes English as a second language?

Answer 1

You can find many freelance editors at website like http://www.getafreelnacer.com/ , you can just post your requirements at the website and let many editors  bid for your project.

You can hire whoever you like.

Answer 2

I am a freelance editor, so I can tell you what I do.

I have to see a sample of a writer's work. Then I set a price for a specific job. I believe that is the most fair way to price work.

I've written a page about the cost of editing on my Web site. I've put it in the source box.