Hi Pakaj,
Good try!
I looked briefly at IBM's site, but I don't think Sun and IBM have that relationship.
IBM have set up a mock exam that you have to register (for free) to take at home, but that doesn't entitle you to the official Sun exam any more than any of the other mocks.
I would also aim to be scoring higher than 70% in the mocks before you take the official exam - work at getting above 85%.
Good luck in your tests