I admit: I looked at some of the other bids. I hope you don't select someone who has typos in their proposal!
It's very difficult to provide a quote for this project. How long is it? Is the content highly technical? What level of proofreading/editing are you looking for? My hourly rate for writing is $50. I'll do "heavy editing" -- which would include significant revising -- for $45 per hour. Editing -- no major rewriting -- would be $40/hour. Straight proofreading -- looking for typos, errors in grammar, spelling, punctuation -- would be $35/hour.
My experience includes 40+ years in marketing communications -- writing, editing and managing/reviewing the work of other writers. I work quickly and can provide a firm estimate for each project, including this initial project. My $750 bid should be considered directional only since I don't have any details about the project.
One more thing: I'm an American, native English speaker. So you'd need to tell me if there are any special Canadian spelling principles I'd need to follow. I look forward to hearing from you. Thank you for your consideration.