We were in Athens last week - jumped off the tour bus in downtown Athens for a short walk down the main tourist shopping street so didn't have much time to get back to Piraeus and took a taxi.
Tour guide had indicated the taxi fare from Athens to the dock should be 15 euros - taxi driver wanted 25 which would be a gouge - we settled at 20 euros and no tip at the end. Two pax - wife and self.
We'd tried a couple other cabs and they were all at the 25 euro pricing with some mention we didn't quite get about a distinction between two types of cabs.
Anyway without having time to dope out something better the 20 euros was ok and got us back to the Galaxy handily.
Kansas City MO