Hmm...based on the 800ct boxes I keep them in I must have roughly 5000 extra cards, not to mention the three 4" three-ring binders that have the up to four copies of Movie Block in my collection...assuming an average of 2.5 copies of each card (reasonable, considering I have close to a complete playset of Fellowship Block with barely a complete set of King Block and Tower somewhere in the middle) that puts me at about 4500 cards in my "main" collection, leading to a total of nearly 10,000 all told.
That's kind of neat, actually. Finally catching up with boyhood dreams of having every card...not that I care about Shadows or beyond.