Originally Posted by
lamphs
Don't know whether or not you have a car. If so, everything is easy - museum is free, except a cost for parking (15 USD). If you don't have a car, then Uber/taxi is best. While the Metro bus to/from IAD can be convenient, each passenger will need a SmartTrip card or have the WMATA app. The SmartTrip card is 5 USD, IIRC, and that does not include any fares.
The bus from the terminal to Udvar Hazy is $2 per direction ( Bus Line 983 to be exact ) and if someone has exact cash ( either USD 1 bills or coins totaling USD 2 per rider ), there is no requirement for a SmartTrip card as the fare machines do accept cash.