Kalun-
I exchanged emails with a fellow named Franco. I asked him if the Fiat 850 lights were used on the GT40 replicas. He confirmed this. The cost was £30 each + shipping and customs. I'm afraid I didn't ask him for the shipping and customs. Generally, US customs is 2.5% of the cost. I haven't a clue as to the shipping costs.
The lights come complete with lens, bulb, and bulb holder.
Send him an email. He is very good about responding, usually within a day.
Bill