This question gets asked over and over again.
General consensus based on a WIDE variety of people around the USA is to try this place first:
http://www.bestrateautotransport.com/800-272-6658
ask for Stephanie and tell her that it is a referral from a Microcar Club.
They are a broker, so they deal with a lot of different haulers, but they apparently are small enough to provide some good personalized service, plus they appear to use rather reputable drivers (so far) that know how to deal with special vehicles. Make sure you have some dimensions and the wheelbase and track length so they know it is smaller than a "normal" car.
So far, everyone using them has had favorable feedback about both the service AND the price.
Example: An Isetta was recently shipped from Chicago to Colorado for $700 in an ENCLOSED trailer!
Your next option is to try a place that specializes in hauling motorcycles. They will generally take a Messerschmitt (considered a trike), don't try and have them ship anything larger though. The more "car like" the vehicle, the less chance there is they will deal with it.
I had a name for one place that I can't find at the moment, will update later when it surfaces.
