coupon poacher
(noun) A person who wait in ambush for stores to restock a sale item to buy in bulk and then turn around sell at an insane markup somewhere else.
Employee A: " Look at that woman, shes been standning in the detergent aisle all afternoon? "Employee b: :she knows there is a truck to night and she is hoping to catch a new shipment of Arm and Hammer for a buck to turn around and sell for 3. " Employee A: "Thats a coupon poacher for you,"