Pros and cons of purchasing out of state

Depending on which two states, there can be problems with registration procedures and tax collection, if you don't do your homework. I've done various combinations of Michigan, South Carolina, Florida, Indiana, Missouri and Oklahoma and have had to pay penalty fees twice because the actions of the selling state (Michigan) changed the taxation category in the state where the vehicle was finally registered, or bumped back the "must be titled by" date to something impossible to meet. One of the worst things that can happen is double payment of sales tax due to lack of a tax compact.