Here are a handful of options for accommodations, all convenient to the McGill campus. If you have any questions regarding locations, please post them in the comments!
HI-Montreal (15-minute walk to campus)
Auberge Bishop (10-minute walk to campus)
University Bed and Breakfast (steps from campus)
Best Western (10-minute walk to campus)
Hilton Garden Inn (5-minute walk to campus) (a bit more expensive, but would be good for sharing with a roommate!)