These posts are somewhat off "rifle" topic, but the question of how goods were paid for is relevent to gun purchases. Did the colonial Pennsylvania Germans barter? From what I have read, that was the primary basis of the frontier economy. Who would have cash? Of course some circulated, but probably not as much as many believe. They surely bartered. And farmers would not trade grain with other farmers, for crops of equal value, they would travel to the towns and trade townfolk for goods that they needed such as hardware, clothing and guns and other merchandise. That's why towns such as colonial Reading set up huge markets in their main streets, to give a place for the farmers to set up. Market days were big events, and these trading days were so popular that large structures were built to house them in Reading prior to the Revolution. People traveled fairly significant distances to make these market days. Therefore obviously rural folk had "extra" goods for the demand to be in place for the "marketplace".
Even townsfolk bartered with each other. For example, stone masons and carpenters helped others build, and traded services for goods and other services. That same exchange occurred between other various trades. People that had acquired some means held mortgages for others, even for properties that they sold (to earn money on "credit"). Incidentally, based on court records, PA Germans took each other to court OFTEN especially for debts due. The British, who generally ran the court system, found these frequent lawsuits to be a curious aspect of the PA Germans. Probably through trading, someone like Moll would have learned of a concentrated demand for guns (and hence want to move to the demand). I would suggest that any narrative or book about this period relevent to exchange of goods and services (especially that tries to establish any assumed commerical operations on this exchange) should include some due diligent research on the barter culture of the day. After all, even as late as the whiskey rebellion in 1794, that rebellion was caused by frontier people that refused to pay taxes on bartered whiskey because they did not have cash.