You can buy new ivory piano keytops from David Warther & Co - his web
site is http://www.ivorybuyer.com .  You can buy new keysets covered
in ivory from Rick Wheeler - http://www.roselandpiano.com  He will not
recover old keys with ivory, and I don't know of anyone who will do
this.

Larry Lobel
Virtuoso Piano Service
Petaluma, California
(707) 762-5800