I live in Canada. Here's a rough estimate of how I graduated debt-free:

EXPENSES

Undergrad tuition: $6,000 per year

Graduate school tuition: $7,500 for 16 months

Total tuition: $31,500 for 4-yr undergrad and 16-mo MA.

Living expenses were about $15,000 per year; total: $82,500.

Tuition plus living costs $114,000 over 5.5 years.

Let's say $115,000 in total to be safe.

REVENUE

Received $22,000 in scholarships and fellowships at grad level.

Received $12,000 in scholarships at undergrad level.

Earned about $12,000 each summer during college, for $72,000.

Saved another $10,000 by working full time every summer in high school.

Total: $116,000.

Result: I finished my MA at age 24 with net worth of about $300. I worked construction for a few months upon graduating to save some money, which lets me float comfortably between short term research contracts while I search for that coveted 'career launching' job. Worst comes to worst, I'll put my boots back on and go find a crew that needs an extra man. My stress level is at an all time low despite my being intermittently employed. But this didn't happen because I'm Superman. I was very lucky for a number of reasons. Here they are, in order of importance:

1) Canada has affordable tuition, at least relative to the United States.

2) I come from a family of carpenters, and thus had a full time job at age 12 and was a skilled tradesman by the time I finished high school. This probably kept me out of jail during that time as well, because I was too busy working to get into much trouble. I actually had to take a considerable pay cut by leaving construction and entering the white-collar workforce. I might ultimately decide 'fuck it' and go back to construction because it pays more. That said, working outdoors in the Canadian winter SUCKS.

3) My Mom forced me to save 90% of my income while I was in high school. "You'll thank me later," she said. I do. Immensely.

4) I was in the top percentile of my high school graduating class, got straight As in undergrad, and had good GRE scores. That produced scholarships. My net tuition payments over two degrees is actually a small profit on my part. That would have been much more difficult to do if I was working while studying like many of my friends were. I know some brilliant people who scored lower than me because they had to work to feed themselves and sometimes their families as well.

TL;DR: My sympathies go to those who have to try to pay $20,000 a year tuition with minimum wage jobs. I never did, but I was very, very lucky.