$300 a month seems low. I went to North Carolina State University, generally regarded as a cheaper school (compared to neighboring UNC Chapel Hill or Duke) for a solid quality engineering education as an in-state student. I graduated after four years in 2013 and my monthly payment to Navient (formerly Sallie Mae) is easily triple that.
Average student loan debt is about $30,000. A 10-year loan at 5% interest works out to about $318 or $345 at 6.8%.
The 5% choice is a bit debatable. I figured most people have some combination of loans at 6.8%, 5% and 3.4%.
Of course there's so much variation between schools that the average might not be too useful, but it seems like $300-$350 is a pretty reasonable figure.
