Some years ago going rate to Nanjing was ard. 1000 RMB. Kind of "exploiting" your situation that you arrived after a tiring flight I guess you would be quoted ard 2000 at PVG and you could negotiate down to 1500 (make sure all toll fees etc are included). Just find yourself a quiet corner as you are outside the arrival hall and take 5 min to calm down and get an overview about your environment. Have a look at all the counters instead of rushing to the first once. That's what I always do in such situations. You been on a flight for 12 hours, so 5 min do not matter at all. Then go to one of the counters saying "taxi service" or "limousine service". Do NOT engage with the guys approaching you with "need taxi? where are you going?" or anyone in an official uniform. Usually these are touts. At the counters you at least have a minimum of security as they will still be there tomorrow while the "nice guy in his official uniform" might not.
According to my understanding 0555h means 5.55 am. As there is only one flight per day PVG-NKG leaving 2130h that would mean a 15h layover for a 1h flight. That does not make sense at all. So 1500 RMB surely is a much better deal that handling all your luggage to the Maglev, metro, train station, taxi etc. just to save some money or wait a whole day at PVG.