I think logically will be, that if only one trader can use the gates - then prices should remain the same, if anyone - prices should be recalculated based on the new shortest distances.
Maybe advanced model cloud be possible, that price is hugely dependable from the time and amount of last stock been delivered: for example - you sold 20 of item to the planet. Timer begin to reduce this amount - 2 in hour for example. After 10 hours, when amount became zero, price shoul began to grow with the same timer.