Merit points could be sold or bought in black markets in the academy. However, it was sold mainly by commoners seeking wealth to send back to their families, and purchased by noble descendants.
Anyone caught selling their merit points for money, even if it was just a report, would be under scrutiny by the academy itself and would suffer severe punishment if found guilty of such charges.
Instructors. Workers. Noble descendants. Commoners. Everyone obeyed the rules.
So it was within reason for the instructors to allow MidnightFire to keep her position as long as she could pay the fine.
How it was done was none of their business.
"4,000 going once."
"4,000 going twice."
"Sold once more, to Miss Bloodberry."
"The next item...."
After that, Bloodberry kept on bidding for each item.
Each time someone else tried to outbid her, she would increase her bid by a thousand or two.
The third item.
Fourth..
Fifth..
Sixth...
Seventh...