According to this article [1], Timbuctoo alone has 60-80 private
collections; of one collection of 5,000 manuscripts, 3,000 have been
catalogued, the balance being kept in chemical limbo pending the funds
to deal with them. Other manuscripts are not even that protected.
The thing that got Gates excited was that these manuscripts contain
not only texts in Arabic, but also texts in songhai, bambara and other
Saharan languages.
Quite how much cash is required to conserve the remaining manuscripts
is not mentioned, unfortunately. Not much in relation to their
historical value, I suspect.
[1] http://www.lexpress.fr/Express/Info/Monde/Dossier/mali/dossier.asp?nom=
so why are the 'private collectors' not paying for the preservation work?