In my setting there are deep stations that hold fuel for ships trying to jump across the void in the mostly jump 1 world. The prices of goods that pass through these stations increases quite a bit due to the increased prices of fuel going through those stations. Of course my players avoid travel like the plague so they've never been visited. 

To the main question, the answer I've always come up with is due to the need of supplies on the side of the smaller economy and the money to make profit while paying the fuel costs down means inflated prices going either way.