This question already has an answer here:
I've received an offer for admission next year. I would very much like to accept the offer, but I'm not sure the 50% TA position will be enough to cover the costs of commuting and an apartment near the university.
During the interviews last weekend, one of my likely advisors stressed the point that when an offer was made (they didn't come out and tell me then, but were very clear that my chances were good) it would be negotiable, but he didn't elaborate and I didn't feel comfortable asking what he meant.
How should I broach the subject of receiving more funding without coming across as ungrateful, and is there any way to know what kinds of additional aid the university might have available?