If you have a number in your head that you feel will make it work stick to it---if the offer is not enough he turns them down and goes to college. Also dont expect big dollars in that round
Was he drafted by the same team that was talking to you all along? If it is this shows good interest so I would wait it out for a few weeks and see what happens
Has the college coach been calling to get updates?
One last thing-- in reviewing the 43rd round picks I do not see a HS pitcher from VA drafted--have you got the correct round noted in your post or am I missing something here.