Interesting. I assume you believe that government should be in the army interest? Should the government be able to negotiate prices with military contractors?
That question is so off the wall that it is hard to take it seriously although I know you intend it as such to make a point. The only way for the government not to buy military equipment from private business is either have no government military but instead to hire one. How smart is that. The other option is for the government to go into business itself manufacturing military equipment. How efficient would that be?
Defending the country is a Constitutional responsibility and I am perfectly fine with the government buying drugs, on a bid basis, for government hospitals like the Veterans Administration.
I am not for the government negotiating prices for drugs sold to the general public even if the government is paying for some of it.