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Do you know how much carbon fiber would be needed to build such a thing?

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No.

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Off the top of my head, I'd estimate maybe the equivalent of 1 million B-2 bombers.

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You're way off. The whole point of the special material is that it is insanely strong. The threads that support the elevator don't need to be that thick. And the platform itself won't be that much extra material.

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Carbon fiber is not "insanely strong", nor is it a "special material". I used the B-2 because its structure is largely carbon fibre-based. How many B-2's worth of carbon fibre do you think is needed for a 10000+km elevator? If the answer is just say 1000 versus 1,000,000 then that is still way too expensive to be feasible any time soon.

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actually it will be built out of carbon nanotube ribbons. They are already being manufactured in america and japan and are much stronger than steel. and we are not that far away from actually building the thing:

"Once secure, a platform-based free-electron laser system is used to beam energy to photocell-laden "climbers". These are automated devices that ride the initial ribbon skyward. Each climber adds more and more ribbon to the first, thereby increasing the cable's overall strength. Some two-and-a-half years later, and using nearly 300 climbers, a first space elevator capable of supporting over 20-tons (20,000-kilograms) is ready for service."

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I'm aware of the strength of carbon-based composites. "Stronger than steel" and "insanely strong" have different connotations to me as a material scientist.