Tom Heller (Lugerdoc) that has already been suggested as a source for a firing pin may have an extractor as well. Originals are difficult to find but there are some excellent reproductions that have been produced that look, fit and function as the originals. You do not want to get a reinforced Swiss extractor that is available however, as it is not proper for your gun.
Gun Parts Sales & Repairs
Tom Heller (Luger Doc)
P O Box 398
St Charles MO 63302
Tel 636-447-3006
Email-
hellerarms@webtv.net