Walgreens: Gain Laundry Detergent $2.99! Do this Deal Scenario in store or Online (choose store pick up) Gain Laundry Detergent 50oz Bottles or Gain Flings 16-Count Packs Sale Price: $4.99 (regularly $5.99) Use Walgreen Digital Coupon: $2/1 Gain Powder, Gain Flings, OR Gain Liquid Laundry Detergent  Final Price: $2.99!