Except that it's near impossible to have a 'small and agile' team that interfaces with a government contract in any way. You need at least one person to just sit in meetings, at least one architect to draw up powerpoint charts that people will buy into, a project manager, a change order coordinator, and an accounts payable/receivable type person to do battle with getting the government to pay you (it is a full time job). On top of that, you need to have had experience doing government work in the past with good recommendations (for which many smaller shops pair up with bigger shops to act as prime contractors, which inflates the price enormously), and you need to have an ITIL or CMMI (depending on the customer) to make sure that all those processes are being followed.

In addition to the two or three people you need to actually do the work, you need a head count of at least 6 more just to manage customer expectations.