The issue I had was one or two places would be very high or low and skew the results, so I got more buy/sell prompts working off the average than hoping for min/max. But same boat as you. Once you have a whole bunch of money, workshops, and caravans, any profit is good enough, you don't need to hold out for high profit. My limiting factor now is finding enough war horses to buy to upgrade my cavalry while I'm trading!