What is the cheapest way to get into Washington from Baltimore-Washington?
Again, make use of public transportation. Board the Greenbelt-BWI Airport Express Line (B30) (202/637-7000, B30 Timetable, PDF download). It will take you nonstop to the Metrorail’s Green Line station at Greenbelt, Md. The bus fare is $3; the Metrorail fare into Washington is another $2.35. Buses operate every 40 minutes from 7 a.m. to 10:45 p.m.; slightly fewer trips on Saturday and Sundays. Check the web site for the schedule.