If want to report people for undercutting then you also want to report people for overpricing cause they are the same and are both bad reasons.
Cause how would that even work? Who determines the price and whats "too little" and and thus reportable/banable.

To me it just seems that you had a way of making money for a while and got upset when people came in and undercut and don't want to do anything else to make money.
I also make money on the MB, mostly via buying and selling. It's all about supply and demand and a little luck.