People need to understand that MIT and most other top tier schools have insanely amazing need-based financial aid programs. If you really can't afford it, don't worry, you won't have to. Yes, you'll accumulate some debt, but it's more like 16,000 instead of 200,000 (at least in my case). Plus, again in my case, it's interest-free for as long as you're in school and 9 months after you leave.
So yes, I strongly advice any high school student from any economic background to apply.
Edit: changed "keeled" to "need" in first sentence; damn phone auto-complete!