The Most Powerful Apocalyptic Supermarket System

The end of the world is coming, zombies are rampant, and humans are hiding in the base to survive. The protagonist traveled through time and was bound to an "infinite supply chain system": as long as someone buys something, he can purchase it from any era in the world. So - while others are picking up cans, he is selling air conditioners; while others are killing zombies, he is selling weapons; while others are seeking survival, he is building a business empire.