This Roundup 1 Gallon Ready-to-Use Weed and Grass Killer drops from $10.47 to $5 at HomeDepot.com with free in-store pickup. This is the lowest price we could find by $6. It includes a sprayer and can be used in and around vegetable gardens, flower beds, tree rings, mulched beds, and more. There is a limit of 2 per order. Sales tax is charged in most states.