More than once I've seen trader's money staying the same after a successful deal (meaning trader got the goods and I got the money) if that deal met the followind requirements:
- at least two types of items were sold;
- items were moved back and forth both by piece and in packs before being sold;
- the first move was to figure out the price ratio by offering and taking back one item with 100-200 gold value;
- the second move was adding more items than this trader could buy and then taking some of them back.
Anyone knows the exact order of things to make trader's money stay after _every_ deal?
P.S.: it never happened with Scamp and Mudcrab, but maybe it's because I never tested their prices.