This is like writing a cost function for a global optimization algorithm for a problem with tons of parameters. You will very soon find out that the optimizer is much more adept at finding highly rated, but extremely useless outliers than you are at writing a competent cost function.

Herein lies the path to coming home to a cart filled with very-cheap-cause-it-expires-tomorrow produce and no tooth paste because it didn't make the cut under some top dollars limit you introduced to fix another optimization loophole.