A colleague has asked me to proof read his thesis, and is willing to pay me for doing so. I have a lot of proof reading experience, and even worked as a copy editor in the past, but have lost touch with the industry since I returned to academia. My question is how much I should charge ? I know that a professional proofreading service would charge up to EUR500 for a 90,000-word thesis, I don't want to ask for this much. I was wondering if any forum members had made informal arrangements like this and how much they paid? Thanks.