We can't use transfermrkt's price to predict his actual price because i believe PSG will still price him far than 30m. They bought him for 95m from Frankfurt, and so dumb if they suffer 65m lose for him. I don't think they will let him go with such price.
If it's around 40m - 45m, that's still acceptable. Nevertheless, i don't think Juve has such money to sign him, and only demand him as loan.

They bought him for 95 million but can't sell him for astronomical fees anymore. Let's say an amount around 40 million like you said. If they go higher than that then Juventus would withdraw from this signing.