shi thouse said.. ....or you could try your luck at buying jerry cans of fuel and selling them on Marketplace!

Nah, too short term, could be good for a few weeks.
Petrol and everything else is going to be $$$$. But its problematic to store and wont be that great when things grind to a halt. People in neighborhood would plan home invasions - too risky.
I'm thinking a quick buck for the next 12 months. For just getting around, during the next few months there could be $$$ in buying electric bicycles, scooters now etc.
Sell em on marketplace for double or triple when cars and trucks are scarce. Just so you can get into town to sell all those family trinkets and stuff for next to nothing, so you have enough to afford a meal.
Mark Australia, this could be your opportunity to get in 10 mins early?