Hi,
I have imported the car to the US myself. Besides the documents that must come with the car (registration and original bill of sale) and a sales contract, I needed 3 forms. One was for DOT, one was for EPA and one was for customs.
My car is a 1972 and it is extempt from EPA and DOT regulations. All you is to check the appropriate boxes on the forms.
You will need all thre forms stamped by customs in order to get the car register in the US.
You can go to the webpage below to download the forms
http://www.nhtsa.dot.gov/cars/rules/import/
If you do not want to do the import yourself you can hire a customs broker who will do it for you. The fee is quite hight for the service.
I have a contact in Mexico City who has helped me with parts and stuff. He also owns at least one DINALPIN A110 and might know somebody who is selling. If you give me you emailadress I will ask him to contact you if you want.
Also on Ebay cars are offered once in a while. But be careful, some of the cars are in really bad shape and overpriced.
Hope this helps and good luck.