You can buy it directly from the maker in quarts and gallons (I guess their largest sku is the 5-gallon pail):
http://www.compliantspraysystems.com/
Or in smaller quantities (like 2 oz queeze bottles) from Beartoothwoods:
http://www.beartoothwoods.com/
I never bought from the maker, but might do so in the future, I liked the small bottles from Ernie, this is a great size for testing the prodct.