In all honesty, Medicare strictly controls the budgetary dispersements to each program (I think it is something around $200k per resident or something like that). A large percentage of the goverment stipend per resident is used to cover insurance, fees, training costs, and to supplement program budget (which is why many PD's get concerned when they don't fill - it undercuts their operating budget among other things). The resident salary is usually fixed hopsital-wide for these reasons, and it is actually dependent on the federal contribution towards a program.
Of note, I was close to overqualifiying for economic hardship on my student loans this year and asked to be paid $700 less to make the income qualification. Due to the budgeting and hospital policy described above, they would not pay me less!
To answer your question, yes and no. The federal government does not make regional allowances based on cost of living for residents, which means your salary will most likely NOT be negotiable (and your financial hardship requirements may be difficult if your program offers a higher base salary). There are, however, certain progams based in private hospitals that may be willing to extend housing subsidization in the form of pre-tax contributions, loans, or grants. It is my understanding that these such arrangements are made outside of your base resident salary and usually involve a third party. I hope this helps...