Yes, we have 1-gallon refill bottles available for all our products, they are on the same Amazon listing as our 18oz bottles and come to around 1/3 the price cheaper per ounce.
To find it, simply go to the same listing as our smaller bottles and once you're on the page, you can select the '18 Ounces' or '128 Ounces' option.
For your reference, you can see all our available products here: CAR GUYS Amazon Store