Square has the ability to program the game to prevent this, they choose not to. As far as I can see the GMs do nothing to prevent this either. Yoshi made a vague "as long as the price is not too high" type of statement, but that doesn't tell us anything. Not too high for a billionaire is much different than what it means to someone living paycheck to paycheck, we need specifics or they need to ban the practice, program against it and take action against those trying to get around the rules.