When I asked about supplies for the system of using expandable plastic rings to connect PEX pipe, the manager of the local Sutherlands Hardware said "That hasn't made it to retail yet". Checking at the other hardware stores in town, I find that he is correct. They sell clinch rings, crimp rings, and push-on ("Sharkbite") fittings. The PEX pipe for sale is not clearly marked as being type "A" or "B". All I've found so far is type "B".
Using the expandable plastic rings is most easily done with a specialized expensive tool and I was really looking forward to buying one. What a disappointment!