When I registered mine, Scotttsdale Airpark, the only thing I had to pay was for the for the license.
I did bring reciepts for the motor, trans, paint etc. just in case but they did not even ask to see them.
I did not pay any state or local taxes.
I did have to pay extra for the plate "NICEASP".
I agree with the other post, pay and avoid the grief and then enjoy the ride.