The cost of editing or proofreading will depend upon the quality, length and complexity of the text and the estimated time it will take.
As a rough guide, for proofreading use a price of €50 per 1000 words as an indicator. For editing, use €60 per 1000 words as an indicator.
There is a minimum charge of €50.
Once we have discussed your project and I have seen the text, I will send you a quotation with a fixed price for you to approve before starting work.