After the great economic minds of Cappy Cappites converged and discussed the retirement debate, I believe Ras Al Ghul had the "most appropriate" answer - make your own moonshine.
This is not to belittle or lessen the other answers/options because (as another reader pointed out) it WILL depend on the environment, you yourself and your personal preferences, and what precisely happens in the economy (complete rapid collapse or just a slow degradation).
However, I believe no matter where you go and where you are the ABILITY and SKILL to make booze will serve you well AND make sure the roving bands keep you alive instead of randomly kill you:
Please make a win-win-win decision.
Buy yourself the book so you can make booze and retire in comfort - WIN!
Buy yourself the book so I can make a commission - WIN!
Buy yourself the book so the author who had the wisdom to write this tome gets a royal check - WIN!