In areas with high living expenses (i.e. Northern and Southern California), there is no way you can get a 1K mortgage unless you have a lot of money to put down. Heck, a nice 800 sq ft. 1 bedroom apartment runs about $1,500/month. I guess you can always look for something cheaper, but do you really want to live in a not so desireable area after putting so much time, effort and money to get a docorate degree???
The monthly payment on a $200k loan based on 6.5% interest and 10 years repayment would be around $2,271/month. Note that the principal balance will actually excced $200k because of the interest that has accrued during the time in school. The monthly payment will actually be higher than this. Lets say the salary after graduation is $100k/year. Now, this is an excellent salary and far above what most in the US make. For a single person in CA, this calculates to a NET pay of about about $4,744/month assuming standard benefits, S1 filing status, and a 10% contribution to 401k. However, the student loan repayment is a big burden. ($4,744 - $2,271 = $2,473/ month available).
So you have $2,473/month to work with. If you live in a decent 1 bedroom apartment at $1,500, that leaves you with $973 for all other expenses (car payment, gas, insurance, food, utilities, entertainment, etc). This will not leave any additional money to pay more on student loans unless one takes a second job or works a lot of overtime.
The bottom line is that these student loans are an enormous burden and the return on investment on some of these private schools that charge $32K +/year for 4 years to attend should be heavily considered if loans are used to finance 100% of the education.