U.S. Gov begs for a low price

I am curious how the U.S. Government does value negotiations with a vendor when they are the only choice? Do they beg? "Please lower your price".

Or what?

As an aside, here is what Australia was briefed in 2006:

Here is what Canada was briefed in 2009:

In the 1990's, having two engine vendors was always part of the JSF snow-job to a gullible Congress. "Look at all that value!"

DOD select acquisition reports on F-35 JSF program health, are now separated between airframe and motor.