"raw materials"? as in metal? plastic? silicon?
No sorry, if Lockeed (just an example) is contracted to build a spaceship, then they are the ones that build it. They may subcontract for certain parts, such as a programmer for software development, they will order raw materials for the project as well, but those things would be handled by Lockeed. In other words, if Lockeed needs to contract out others to complete their own project with NASA, then Lockeed handles the payment to the subcontractors, not the government. However the money used to pay the subcontracts will come from the same money paid to Lockeed from the government.
NASA does not own any companies. Even the organizations they give grants too, comes from us, not from NASA. The only money NASA employees actually do get to see is their own paycheck, which also comes from Treasury.