Are you looking at orchestral/classical programs? If so, there are a few options. Some schools guarantee full scholarships, some almost always offer one, and others can only do so for certain students. The best way to find out about scholarship opportunities is to contact the admissions departments and professors at whatever schools interest you.
Curtis will provide free tuition but will leave living expenses to the students. Colburn offers free tuition and free room and board. Neither offer true graduate programs, but you can get an artist's diploma. Curtis is also a little bit weird about taking older students, but it is possible.
Yale offers full tuition and possibly a small stipend. Rice almost always offers full tuition to graduate students.
The New World Symphony isn't a school so much as a training orchestra, but they actually pay a reasonable stipend.
Many schools in Europe are remarkably cheap and worth investigating. Some will offer stipends.