In my experience, as has been posted here somewhat, all states handle things a little bit differently. Some (Virginia & others) tax based on the cost of the kit and maybe the engine, but not everything completed. Others (Florida & others) tax based on every red cent that went into the cost of the build, including shipping, labor, etc. Others (Delaware & others) have no tax on aircraft.
Florida won't charge a use tax if you have owned the plane for at least six months and it hasn't entered the state during that time. I am sure other states are like this. Florida used to send tax bills to planes that flew to Sun-N-Fun, but they stopped doing that. They will, however, investigate planes that changed from Florida registration to Delaware registration, for example, because they know that people sell planes in state and the new owner registers the plane out of state.
A lot of states, including Florida, will bill their sales/use tax rate on a plane, but will reduce the taxable amount by the tax paid to another state on the same transaction. For example, if I buy a plane from a dealer in Florida and they charge me 6%, but take the plane to my home in Indiana, they would likely only charge me 1%.
What a lot of people have started doing, is creating an LLC, usually with the N-number as the name of the LLC, and paying the necessary tax at the time of original registration. Then, when they go to sell the plane, they just transfer ownership of the LLC, so the plane does not change ownership, so there is no taxable event if moving to another state. This is done regularly with boats and things like that as well. There are added complications to having an LLC, but in many cases, especially if it's a Delaware LLC, or one of those states that makes it easy, you can pay a small fee yearly to a company that manages everything.