Fecals aren't usually too expensive. I can get one done around here (central MI) for under $20. Every vet is different of course, but your brother shouldn't have to pay through the nose for a simple fecal test. Now if the bp does have parasites, the meds for that might be a different story depending on what's needed.

The new snake could have loose stools simply due to stress in a new home. I assume your brother knows to give the snake several days at least to settle in before he handles it? Stress could be the cause...

Another thing, seperate tanks isn't enough of a quarantine. The new snake should be in an entirely different area of the house and hands, clothes, etc should be THOROUGHLY washed before coming in contact with the first snake and it's enclosure. If this is a disease of some sort, the first snake could be in jeapordy if the new snake is anywhere near.

Vet visit is step one and, yes, your brother does need to get that fecal done. Good luck!