By Sean Coughlan
BBC News education and family
The top universities in the US are now charging more than $50,000 per year
Here's a figure that will chill the blood of any parent thinking about sending their child to university.
It's a price tag of more than $200,000 - about £132,000 - for a four-year undergraduate course at one of the leading universities in the United States.
It means that as well as student loans there are also parent loans - with huge sums of money borrowed by people who might have been planning for their retirement.
And it's the middle-income families who are facing the toughest squeeze.
In England a major review of university funding and students' fees is under way. What would happen to the cost of going to university if there were no fixed limits?
'Established for advancement'
Boston in the United States, with its concentration of universities and colleges, provides a thumbnail sketch of what a free market might produce.
MIT pays more than $80m in financial support to students
In the entrance hall of the Massachusetts Institute of Technology there is a carved sign that reads: "Established for advancement."
And it raises questions about higher education that are being asked across the developed world: Whose advancement? And who is going to pay for it?
Does a university exist for the advancement of learning? Or is it there for the advancement of society and the economy? Is it there to help social mobility? Or is it there for the advancement of the individual student?
Students who make it through the tough competition for a place at MIT will be paying for four years at more than $50,000 (£32,600) in annual fees and charges - a figure not unusual for the leading institutions.
So what does this mean for anyone wanting to be a student here?
Elizabeth Hicks is in charge of student financial aid at MIT and she admits to being very worried about the sustainability of the current system for supporting students.
President Obama has warned of families unable to afford college
"I'm afraid we're at some kind of tipping point," she says.
Even though the cost might seem sky-high, she says the real cost of tuition is double what is charged - and the university has to use endowments to subsidise student places.
It also expects to spend more than $80m (£53m) in financial support to students - so that it can recruit the best students regardless of their family income.
"But families are still shocked by the sticker price," she says, particularly those caught in the "middle income squeeze".
The rich can afford the cost (about a third of students get no support at all) - and the poorest will get the maximum support from scholarships and state aid.
But for the majority in the middle, who might already have been saving for college, it means a major stretch on cash and borrowing.
In terms of the toughest pressure point, where the support fades away and the big bills arrive, she says it is for families with a combined income of around $130,000 (£86,000).
Changing jobs market
What makes it even tougher for families is the feeling of being caught in a double whammy.
Student Marsida Tirana says the system isn't fair, "but life isn't fair".
They might not really be able to afford to send their children to university - but they also feel they cannot afford not to send them.
Well-paid, blue-collar manufacturing jobs are disappearing - and without a degree there is the fear that youngsters will have to rely on insecure, badly-paid service jobs.
President Barack Obama, pledging more financial support for students, described this fear over costs as "the college acceptance letter your child had to put back in the envelope".
While families are having to take out the equivalent of another mortgage, there are other consequences for universities. How can they find the best students if cost becomes a barrier?
"We're selling places for half the real cost. But we don't just want people who can afford to pay. We're really committed to diversity. We don't want it to be simply an institution for the privileged," Ms Hicks says.
She also takes a longer-term view on the pressure on student finance - having looked after the US Department of Education's student finance programme under the Clinton administration.
'Who should pay?'
Student support for many universities was once a couple of people operating out of an office, she says, now it's a massive, multi-billion operation, trying to achieve the balancing act of funding the huge rise in demand for university places.
Kristen Smith says cost is a major factor in choosing where to study
"I worry about how sustainable this is... There is an expectation that more and more people will want qualifications to help them succeed - and it should be a top priority for government.
"But the question is: 'Who should pay?'"
From the perspective of the funding debate in England, another difference with the US system is the way that the different "price points" create such a variety of options.
There are about a hundred different universities and colleges in the Boston area.
These include international giants like Harvard and MIT, but there are also similarly-expensive major private universities such as Boston University and Northeastern University.
Along with the traditional, non-profit private universities, there is also a growing sector of for-profit universities, which have been buying out some of the smaller colleges.
There are also specialist institutions - such as law schools and those with particular religious affiliations, all with their own menu of prices. Even within universities different courses will have different prices.
Elizabeth Hicks fears for the future sustainability of the funding system
For medicine, the tuition fees alone - before any other obligatory academic charges - can be in excess of $50,000 (£32,600) per year.
And at the other end of the scale, community colleges offer a route into higher education for those with less cash or those working and wanting to improve their qualifications.
These charge by the individual course credit - and studying might be spread over a number of years. In Boston, the cost of 20 credits at a community college might be $3,000 (£1,955).
Among the biggest providers of publicly-funded higher education across the United States is the network of state universities.
Boston has one of five campuses of the University of Massachusetts. It's an airy, modern building on the waterfront, a few subway stops away from the city centre.
Many of the students here will be the first in their family to go to university - and spokesman Will Kilburn says that is a reflection of the huge expansion in recent decades of people wanting to go to university.
The old industries are disappearing and he says more and more families feel they need to get their children into university - fearing the tough life of the minimum wage and insecure employment.
Students from Massachusetts receive a discount here, paying about $12,000 (£7,820) per year in tuition and fees - half of what out-of-state students are charged and much less than other local universities such as MIT or Harvard.
Students here are keenly aware of both the cost of their courses - and their relative worth in the academic pecking order.
Psychology student, Kristen Smith, says she expects to be in her forties before she pays off her university debts, which are already at $80,000 (£53,000) and rising.
And she says unambiguously that students are choosing universities based on cost.
It's a big sacrifice for herself and her family, she says, but worth the investment. Not going "was never an option".
But despite the scale of the cost to all students, she fears students from the more expensive universities will have an unfair advantage in the jobs market.
"It's not fair that because you go to Harvard you get a better job. We start behind the pack and have to work harder to get the same accolades," she says.
A sports student talks of his worry that his single-parent mother has used her retirement money to pay for him to go to university.
Business student Marsida Tirana says young people of her generation face years of debt, leaving people in a "crazy situation".
But she says an even greater fear is not going to university at all. "It's not fair. But life's not fair," she says.