Why would you hack saw a coin when bolt cutters do just fine? It's gold! You lose the filings, then you're going to melt it back together, you'll lose propane and oxygen doing that when you can use that for heating your food. Seriously I'd be more concerned if my refridgerator went offline than if people stopped accepting debit, credit, and paper.
If you're looking for a coin for that purpose, get the coin of your "realm" or country. USA, go for eagles. Canada, get maple leave. Et cetera. Gold is gold but a good bullion coin should be easy to recognize.
One also has to look at what type of purchase will be made. On a daily basis you may lose many ounces due to chiselers taking advantage of a bad situation (like selling water on hot days). Get a 10 ounce bar (silver) and buy your food in bulk - but I'll bet you your grocery store employees have no idea how to transact in this fashion on the whim and how to tell a fake, nevermind the amount of trust you put in into your grocer if you even know their first name.
Groszy, I like how you think. We're so tamed by the whims of the Western marketplaces and how they set the prices and the establishments set the taxes, most people don't even know how to haggle or that it's even an option.
Edited by Libertad
01/14/2015 7:48 pm