Which would be the cheapest way from Airport to Kropiggi I understand it's about 1 1/2 hr journey
Taxi is about 60 € from the airport! If you need an adress contact me so i can hook you up! As mentioned before cheapest way is by Bus (K.T.E.L Halkidiki) You would have to take a bus from to airport to the halkidiki central bus station and then a bus from there to halkidiki which will cost like 20 € in total!
Hellenic island services do the transfer for the main holiday companies so you may be able to book a transfer with them.