Posting unfounded suspicions instead of actually testing things only creates white noise on the forums...just a thought
When you haul rare goods to a station that sells rare goods itself, you get "low price / low supply" bug:
(numbers are the same for the two stations I tried, not sure if they are the same across the board)
Initial supply is 2 tons, average galactic price is 110, buy/sell price is around 200. This is for both rare goods the station sells and rare goods you bring in, obviously supply number is just for goods being sold.
If you wait for the next price update (~15 mins I think), both prices and supply jump back to the normal values.
This bug doesn't seem to happen when you go to a station that doesn't sell rare goods itself, at least I have yet to trigger it on a normal station.
Going to a normal station to sell, then going back to buy doesn't create a workaround - you still have to wait for the next price update. Staying outside of the station (i.e. travelling around the area) for longer than 15 mins doesn't help either.