I graduated from Harvard Law School. When I was coming through, everyone who wanted to work in a large law firm paying top wages (which now would be $160,000/year) had multiple job offers from them. I was in the lower 40% of the class but I had job offers from those types of firms all around the country. It's still the same today, despite a much worse job market. So an HLS degree is a ticket to high-paying jobs, and even if you are terrible as a lawyer, you can bounce around from one high-paying job to others for at least around 10 years, and easily repay any law school debt. (Some people didn't want this, and they just found jobs in public interest organizations or the like, and others ended up clerking for the Supreme Court or other prestigious courts.)
Columbia U. has the best job record of any law school in the country since it's in a legal gold mine, NYC, and it's just easier for more firms to come to campus to offer jobs.
No state school even comes close to that employment track record. UVA, Berkeley and Michigan are the only state schools that have top law schools, and even significant portions of their classes don't get jobs.
Look at http://www.lstscorereports.com/national/ for the full numbers on jobs, costs, etc.
Finally, while where you go to law school matters less as the time out of law school grows (and your client base and skills matter more), going to Harvard or the like gives you a significant starting advantage in your career (and thus a significant starting advantage in growing your bank account).
But, please--comparing a typical state school to Harvard?
Well you have the right to disagree with the AG 's office. It is the judge who ultimately decides the proper and legal amount of support owed. I have never heard of an AG doing something this overboard. Do not sign the agreement! Insist upon taking the issue before a judge. If you have already signed it then that is a different story because then you need to get an attorney and try to modify the terms of the court order. You might also try to talk to the caseworker's supervisor.