You find an antique roadster for sale. It's one of a kind; exactly the kind
of car you've always dreamed of owning! You offer $30,000 for the car,
and the owner agrees. Just before you are scheduled to pick up the
car, however, the owner changes his mind. Your dream is gone in an
instant!
What do you think would happen if you sue the owner to force him to
honor the deal?
A court would do nothing; deals fall through all the time.
A court might award you money damages.
A court would probably require the owner to sell you the
car.
A court might give you the difference between the price of
this car and the price you would have to pay to buy the car
from someone else.