Whats the cheapest way to get from Downtown Baltimore to Dulles (IAD) airport within 2 hours?

I need to catch a flight out of Dulles and dont want to spend $100+ on a taxi. Is it possible to take the MARC train to DC and then catch a taxi from there? are there even taxis outside of union station to hail? supershuttle? thanks

2 hours from Baltimore to Dulles? Good freaking luck. Unless you plan on going at 2:15 in the morning on a Wed, and thats still a reach. Out of Baltimore, around 695, down 95, around 495, over the American Legion bridge and down Dulles access? Again, fat chance. Call a friend and offer to pay for his gas and a case of beer.

{EDIT} I misread the question thinking that you were going from Dulles to Baltimore - basically take my answer and reverse all the steps but you're not going to make it in under 2 hours from Penn Station to Dulles. I hope your Dulles flight is over 2 hours late because that is the only chance you have with public or private transportation. Maybe a Baltimore City cabbie can take you to Dulles - but not for less than $75. {/EDIT}

Your only bet is the B-5 bus from Dulles to the Orange Line (Rosslyn Station) to the Red Line (Metrocenter Station) to the MARC Train at Union Station. If you're lucky and time all the connections correctly, you could make it in a little over 2 hours - not including travel time from Penn Station to your destination in Baltimore. The good news is that the total fare will not be more than $15.

I have 2 ideas. The easy way is to find a friend with a car, and offer him $50 to drive you to Dulles. Unless you're going in rush hour, you can make that in an hour, or maybe a little more. Piece of cake.

Second way is MARC to DC Union station, then Metro (red line) to Metro Center, change to orange line to Vienna. Get off at West Falls Church, and catch the express bus to Dulles.

Yes, there are plenty of taxis at Union station.

Good Luck. Maps have it at an hour, but take that and at least double it because of the traffic on beltway. When are you travelling? If it's before 10 am or after 3 pm on a weekday forget it!