I've edited for friends for as little as dinner or drinks. I've edited friends of friends for some money, but always at an hourly rate. That's what I'd recommend. As a student and an amateur, you don't (and shouldn't) have the clout to charge someone nearly a thousand dollars to look at their work.
First, confirm with your customer exactly what they want. Are you just proofreading for spelling and grammar? Will heavier editing be involved? Are you going to have to do a lot of rewriting? Some papers I've edited have been a breeze. Others I've done from ESL people have been absolutely nervewracking, and I soon found myself regretting having agreed to a fixed price so soon.
If the person is a good writer already, maybe you should charge something like $10-15 an hour to look at their thesis, which will probably take a few hours and get you around $50. If the person is native Chinese or something, maybe you'll spend an entire week editing, rewriting, and re-editing their entire thesis, so you'll get more like $200-300.