Trader will not pay a full price, never.
First off, there's always a little chance that he can escape.
Second, if he dies, he looses no more than the full price. He can easily switch the route to avoid the system he was killed in, and the "bad pirate" gets nothing.
Math-wise, current worth of the cargo is (sell_price - buy_price) * time_spent_on_the_route(current_position) / full_route_time(route_length) + buy_price
So, if some smart dude is asked for full price when he did only 90% of the route, he prefers to die, because it's better profit-wise.
