Firstly, a B-1 isn't a B-2.
Secondly, the unit price of a B-2 wasn't that high, $1.157 billion according to the
USAF. Even that's exaggerated because of sunk costs. In May 2001 Northrop put forward a proposal to build 40 new B-2s at a cost of $545 million each.
As a comparison, the construction cost of CVN-76 Ronald Reagan is $4.3 billion. The procurement cost of the air wing is $4 billion+. That's not counting the annual operating costs of $160 million, and the need to store the nuclear fuel for a few millennia afterwards....
(Buying new B-2s would also have saved the tax payer over $100 billion over the next 30 years. The Lexington Institute estimated the cost of keeping the present mixed, and aging, force flying until 2037 as $220 billion. The cost of a pure B-2 bomber force of 100 aircraft, including procurement, over the same period was estimated as $120 billion.)
Academic of course, Congress wasn't interested and they'll need every airframe they've got to make the present fleet last long enough. Sustaining the present bomber force till 2037 is predicated upon only losing a B-1 every five years and a B-52 every decade. The actual loss rate is running at a B-1 every 2 years and a B-52 every 5 years.
So no spare aircraft for sale I'm afraid.....