Im no expert, but ive heard quotes are around 200m for a new stadia.
The foundations under Goodison are 120? years old, the plumbing, every single brick, no way does most of it even get past planning, they seem to think it could be done in phases while keeping the ground open, its ok if your just sticking a tier on say The Park End, but anywhere else and im telling ya, it cant be done. It will cost a lot more than 200m.
Look if these lids think it can be done, fair play, but for all the plans, I havent seen a single figure about how much it will cost.