If you're entering a field of study which will most likely lead to grad school once you've finished your undergraduate degree, there is a new study out of Georgetown University you should read about.
The study looked at the additional cost of various majors as compared to what that graduate degree means in terms of extra income in your new field. Some of the results surprised me even. Some grad school graduates made less than 1% more than undergrads starting in the same field. But a few made over 100% more than undergrads in their field just starting out.
The details can be found in the following article I found at dailyfinance.com.
Grad School Math: Which Degrees Are Worth The Debt?
While it's still a smart idea to try and have as little debt as possible once you're finished school - spending that extra money for certain grad programs may actually be worth it in the long run.