Take it to a luthier, not a music shop.
Foster at Foster Guitar Works, Jan at Stellenbosch Guitar company and Matthias/Matthew at Casimi are all likely to have a few Tusq and bone saddle and nut blanks.
I think all of their contact details will be listed on that South African Luthier trhead:
http://www.guitarforum.co.za/setup-mods-and-repair/sa-guitar-luthiers/