I wish I could say that (15 years post graduation!). In which case, time becomes an issue -- some decent places, but you'll be spending an hour at least to eat there, e.g. L'Espalier. It would make for a fascinating year in college though -- eating lunch at every decent spot within a mile radius. Shame one needs to study as well.
How much do you want to spend?
There are lots of places in the area but most are relatively expensive. Ethnic places tend to be the less expensive - Steve's is a good choice. Follow Berkeley St south over the Pike and you will find Billy's Sub Shop and Berkeley Perk, both with good stuff at affordable prices.
Billy's Sub Shop
57 Berkeley St, Boston, MA 02116
Berkeley Perk Cafe
69 Berkeley St, Boston, MA 02116