fee example
Although it is difficult, if not impossible, to give a reliable estimate of charges for editing or writing without seeing a sample, it is at least possible to give some idea here of what I would charge to edit 'average' writing.
So as a rough guide, I charge $30 per 1,000 words for copyediting. For large jobs I reduce this slightly, as I also do for regular clients.
If you would like a firm quote, then I would need to see a representative sample of the work to be edited.