This action allows Boeing to manufacture the third core stage in time for the 2024 mission, Artemis III, while NASA and Boeing work on negotiations to finalize the details of the full contract within the next year. The full SLS contract is expected to support up to 10 core stages and up to eight Exploration Upper Stages (EUS).
From 2011 through 2018, the SLS program had expended funding totaling $13.999 billion in nominal dollars. This is equivalent to $15.109 billion in 2018 dollars using the NASA New Start Inflation Indice. This is basically the same Space Shuttle technology that the same companies were trying to adapt for the Ares and Constellation rockets. There has been only one test launch during the Constellation program. The first SLS launch has now slipped to about 2021.
The SLS program has been getting $2.1 billion per year without actual launches. A program of ten launches from now to 2035 will likely cost $4 billion per year. This will be $60 billion. The contract will be whatever costs are generated by Boeing and Lockheed and an additional ten percent.