right now i live in japan (u.s. military) and would like to take my '94 toyota supra with me when i transfer back to the states. i'm wondering how much it will cost, what papers i need, how difficult, etc.
i forgot to add that the car has a lot of sentimental value, in addition to being in great shape. i realize it would be expensive, but i am prepared to spend 20k+

I agree that it would be prohibitively expensive to modify your Japanese spec Toyota to meet US standards for import. Check with your local Base Exchange to see if they have any programs for you to buy a new car for delivery when you get home. Used to be you could get a pretty healthy discount on some car brands.