The activator(as its called) is nothing more than Food Grade citric acid . Depending on your location, you often find this in the canning and preserve sections in major food stores. However, you can also get citric acid in Drug Stores and/or health food outlets. And finally, you can buy it online pretty much anywhere in both small and large format(bulk) for very little money(50lb under 100USD). Though you'd have to factor shipping in there too.