The main prepper whose account I read had a great post-mortem on his first prep effort, that basically went "lots of chocolate and DVDs and other small luxury items". Gold jewelry wasn't even the thing he was investing in to exploit the black market: a massive DVD collection was. Accessible luxuries like a movie you haven't seen are gold in those conditions. People can sock away 100 kilos of rice, but after six month's eating only that, they'll kill their own children for a bit of chocolate.