Amazon offers Prime members the Roundup Weed and Grass Killer Concentrate Plus 36.8-oz. Bottle
with free shipping
. (Non-members can spend $35 to qualify for free shipping; otherwise, it adds $7.94.) That's the lowest total price we could find by $16. (For further comparison, it's tied with what local stores charge for 32-oz.
bottles.) It makes up to 12 gallons and is purportedly waterproof in 30 minutes.
: The price has increased to $18.88