Anz,
Currently I am a senior NCO in the Navy and this is my experience from being in the Navy. Marines may be different, I am not sure. Your son can request to fly into any airport that is cheaper or pay a difference. For example, If he wants a stop at gso and then go into norfolk, he will have to pay the difference if their is one. If he wants to just fly into GSO and have mama drive him up to Norfolk, he should be able to do that without an added charge as long as it is cheaper. From what I have encountered, junior personnel do not know the requirements, nor are they advised that this is an option. I would have your son inquire about these two options ans see what can be done. Another option would be to see what a roundtrip tricket would cost from GSO to ORF and just use the one portion if he can get into GSO or turn around and use both portions if he has no other option but to fly into ORF. Realize there is another airport with pretty cheap flights in Newport News, VA, about 15 miles from Norfolk