It’ll be way over $100k for an ev drivetrain. Realistically close to $200k. You’ll never make up the savings. And you’ll definetly need a donor Tesla or something similar or how else will you control the battery motor and charging functions ? And all the cooling pumps , battery cell management etc. ….
Not to mention the mods to the chassis and suspension that will be needed to both house the battery packs AND support their weight.