Boston is an expensive city, and it can be difficult to find off-campus apartments that are within reasonable price ranges; however, that doesn't mean that it's impossible to find good deals. A lot of Northeastern students work for real estate companies in the Boston area, and most real estate agents understand that students are especially under a tight budget. Northeastern also has off-campus housing services where you can work with the school to find a place off campus to live. Getting a cheap deal on apartments really depends on what you're looking for. If you're OK with sharing a bedroom or living farther from campus, then you should have no trouble affording rent in the Boston area. Most of the off-campus housing in Mission Hill and around the suburbs of Boston is very nice and a lot more spacious than the apartments right around Northeastern on Hemenway, Columbus, or Huntington. The few drawbacks to living in these off-campus areas are that they aren't as safe as the areas close to campus and that you are living in close proximity to Boston residents who do not always tolerate college kids.
Living off campus also means that you're responsible for paying utilities, Internet and cable—all expenses that you don't have to think about when living on campus. Living off campus, you have to deal directly with landlords, and the University cannot help with any living issues that you may have. Most students move off campus during there "middler" or junior years and really enjoy the sense of freedom off-campus housing can provide. In fact, the majority of students chooses not to go back to living on campus after having the off-campus living experience.