To build anything takes resources and if we ramp up too fast, we would hit capacity limitations. I. E. would we run out of steel making capacity? This requires a system capacity and systems approach and a linear programming approach, looking at the different resources needed. Do we use steel capacity to build new rails so that the different components of a new energy infrastructure can be shipped at a greater efficiency or is it better to use that capacity to construct the windmills, etc. first.
We have to figure out what is feasible before we can vote on it, and a dollar approach isn't the first one. The price of lithium or antimony only tells you what is available for a marginal or small change, not a big one. (Admittedly, this concept is relevant to decision making about moving a nation in a grand sense, whether for war or military accomplishments, whether participatory democracy, conventional democracy or a dictatorship.) The cost of a teacher doesn't tell you whether there are enough teachers to halve class size.