I looked at the AMTRAK site and the fares were actually quite reasonable...$36 one way from Union Station in DC to Durham. If you wanted to combine the university visit with a DC visit, that might work. There's only two trains a day, with the one at 1050 having a 1715 arrival, one long train ride. The other train doesn't arrive until after 2200. The return trip from Durham is at 1037 with a 1705 arrival in DC.