I sold a car to a friend out of state, how hard will it be to go to court?

It probably won't be hard, but if may be expensive becasue you may not be able to assert a claim against an out of state defendant in small claims court (check with the clerk of your local small claims court to see if its rules permit suing an out of state defendant there), which means that you'd have to sue in another court with higher court fees, unless you are close enough to your friend to be able to sue him in his local small claims court.  Of course, a Court can only give you a judgment.  Thereafter there are a lot of ways that you can try to collect, but ultimately if your friend doesn't have enough to pay the judgment, you may be able to force him into bankruptcy, but you will not be able to collect.