Hi,
From what I have read ( no first hand experience or knowledge here) they can test for inclusion bodies in some organs but not finding any doesn't gaurantee the animal doesn't have IBD as the inclusion bodies might simply be somewhere else in the animal.
But given the short life expectancy of ball pythons with IBD I would say if it is still alive at the end of the 60-90 day QT period you are in the clear as far as that one disease stands.
So, while a vet check might be a fine idea for new arrivals, I wouldn't bother paying for that particular test.
dr del