It now costs about US $20 000 per kilogram to put objects into orbit. Contrast that rate with the results of a study I recently performed for NASA, which concluded that a single space elevator could reduce the cost of orbiting payloads to a remarkably low $200 a kilogram and that multiple elevators could ultimately push costs down below $10 a kilogram.

This article provides a good summary of the technical challenges involved in building this thing. Its still a bit scifi but its close...

IEEE Spectrum on Space Elevators