Hi Queenie,
For 3.0, from the PHB page 248:
Arcane Material Components: The eye of a hawk, an eagle, or even a roc, and nitric acid, copper, and zinc.
Wizard, Sorceror, or Bard Focus: A mirror of finely wrought and highly polished silver costing not less than 1,000 gp. The mirror must be at least 2 ft. by 4 ft.
Cleric Focus: A holy water font costing not less than 100 gp
Druid Focus: A natural pool of water.
You don't need the spell for a crystal ball, but you need the Scry skill to use the spell or the crystal ball properly.
For 3.5:
same components and foci, but there is no Scry skill anymore.
Does this answer your question?