Is there something missing in the OP?
Rim Guard is a fairly unique product. It requires special equipment to install it. Therefore they sell it only to people willing to buy it in bulk, which saves everyone (manufacturer, distributor, end-user) money.
Unless you are in a position to buy drums/totes, there is no reasonable expectation of buying the "stuff". OK, you may find a dealer wiling to pour out a few five gallon buckets, but my guess is that it won't be any cheaper than having them just put it in for you. And then you need to figure out how you're going to get syrup into your tires.
As I said before, Pete's Tire Barn will come to your site and fill your tires for no extra charge. If they don't serve your area, there may well be a similar service available.
Why are you trying to do it yourself?