Triple K makes replacement grips and magazines:
Century sells 60s surplus ammo too, $5.95 a box but if you buy in bulk their flat rate shipping might save a few bucks:
Numrich shows sold out on your safety parts, but IIRC the plunger is essentially just a short rod with the end rounded off. You chould be able to make one and find a spring to fit.
At one time, a company made 9mm Luger conversion bbls for these, they required fitting but once installed they let you shoot readily available 9mm ammo in them with just a drop in bbl change.