This is admittedly picking the low-hanging fruit. Sue me.
Here is a facebook group that claims gas prices can be lowered substantially if everyone refuses to purchase gas from ExxonMobil. Not buy less overall, just buy it from different companies. 545,000+ people who need introductory economics.
Here is another group which supports a legislated price cap of 79.9 cents/litre. 131,000+ people, and the group is exclusively targeted at Canadians. These people really, really need introductory economics.
I could keep going like this for some time. Kinda depressing, really.