I'm sure Motorex's prices may seem high at first glance but when you research the shipping costs (most likely you will have to ship it in a container) it may not seem that high(remember they do run a business). Also , there is a lot of documentation you will have to have in hand for customs before the car lands in the U.S.
For a first timer it is usually tedious and time consuming, you may even feel you are running around in circles. After importing your car you will
still have to turn it over to Motorex to may it street legal (emissions etc.)
if you still want to try it yourself here's what you can do
1 Look for a Customs Broker who is familiar with importing cars .
2 Check with some shipping lines for shipping rates from Japan to your nearest port (
www.mearsk.com, ).
3 Get a quotation from Motorex for legalising the car.
However I would suggest that you let someone who knows the procedures save you all of this stress.