Thumb Score: +16 Amazon [amazon.com] has 1-Gallon Spectracide Ready-to-Use Weed & Grass Killer on sale for $6. Shipping is free w/ Prime or on $35+. The Home Depot [homedepot.com] also has 1-Gallon Spectracide Ready-to-Use Weed & Grass Killer on sale for $6. Select free store pickup where available.