Price Effective Way to do LEGO MILLS?

The most cost-effective approach to constructing LEGO mills involves knowing what bricks are cheapest, this is what they are.

2×2 Brick: https://www.lego.com/en-us/pick-and-build/pick-a-brick?designNumber=3003
16×16 Plate: https://www.lego.com/en-us/pick-and-build/pick-a-brick?designNumber=91405
Baseplate (on sale) https://amzn.to/3tEN3Uh)

Spreadsheet: https://docs.google.com/spreadsheets/d/1ICkRJxlV3f6sO74BYmnfQ0m7f4Y_KZxCvzoNi9dF9kE/edit?usp=sharing

Merch: https://www.etsy.com/shop/TimsLittleShop