Stock up on Emergen-C Vitamin C for nine cents at Target! They are on a gift card promotion through 8/13: buy two and receive a $5.00 Target gift card. Buy two 10-count boxes and use two $2.00 printable coupons. Receive the gift card at checkout, making each box $0.09. I found the 10-count boxes in the trial/travel section at my store.
If your store doesn’t carry the 10-count packs, the larger size also makes for a nice deal: