So hopefully less than $3.6 billion in cells (factory direct, new factory aimed at reducing costs). There is a bunch more of stuff in the integrated units, at the quoted $3000 price, 4.3 million of them would be ~$14 billion.

I think pumped storage is great (I've posted enthusiastically about it here in the past), but the sneaky factor is that they did a good job siting the ones they built decades ago, many of the great spots to build them are in use already.

(I edited in the $14 billion after I realized I was talking about a product with a proposed price, I had originally said something about less than $10 billion)