I second @iamemily03. Although first off I don't even know how I'd go affording the first year with no funding, even if I bet on getting an assistantship in my second year. In the best possible scenario maybe I'll receive the $25,000 federal unsubsidized loan and a $62,395 graduate PLUS loan. But $87,395 is a lot of money to ask of someone, even if the Columbia name is attached to it. Given that I want to go into the public service (like most of us), I don't even see myself making $87,395 until mid-career. And a TA position in the second year only takes off $12,000 in tuition. I feel like it would be a burden I would probably be carrying around with for the rest of my life.
So definitely up for negotiating, and if I don't get any money from that, I've received much better offers elsewhere. The whole point of graduate school is to open up your career possibilities and if my options are limited to careers that I don't feel passionate about (even if they're high-paying) in order to pay off my debt it's not worth it.