Nevada does not charge sales tax on a private vehicle sale.
What the other state does depends upon the other state. If the transaction is here, it is likely that it can't tax it and would have no good mechanism to assess it anyway, but I wouldn't at all be surprised that some state or another has an exit sales tax or some such nonsense that it attempts to assess.
If it is registered in the other state, you will need to register the car in Nevada. This will probably involve re-titling the car in Nevada. It is unlikely that you will have tax liability from any state due to a private vehicle sale, but you will need to look at that state's law. If you are buying on some forum like Ebay, that should be handled through the site. Generally those types of forums can answer all your questions about logistics.