I think not said:
He obtained permission from the Ottoman sultan to remove them - he didn't actually purchase them. Apparently it was a diplomatic guesture on the part of the Turks. I guess the Turks didn't mind losing history if it wasn't their own.
http://www.thebritishmuseum.ac.uk/compass/ixbin/goto?id=enc852
Another book on my looting and pillaging reading list for anyone who is interested is:
The Rape of the Nile: Tomb Robbers, Tourists, and Archaeologists in Egypt by Brian M. Fagan