[David]

Any foundry should do. I was at a pump casting shop a while back and was really surprised by their material supply room. It's exactly what you'd expect, but it seemed weird. Everything you'd need was there. Bins of pure copper, nickel, molydoneum, chromium, vanadium, aluminum, carbon, titanium, etc, etc. They should have a lab on site to check the purity of the vanadium.