The Chilean Class 1 Medical Certificate cost U$D 180 did mine in April... Commercial License renewal is every 1 year if you are under 40 years Old... and Every 6 Months if you are up to 40 Years Old or ATPL.
I know from a friend that in Argentina, Flight School Owners are quite nasty about giving away proper flying hours certificates or stamping your logbook when you leave before he wants you to go.
Anyway the Patagonia and Tierra del Fuego is quite a good place to learn to fly, very challenging. And since its qualify as an isolated zone or something like that, Fuel price receive Subsidy from Argie Government, so is quite low compared to Chile and the rest of Argentina.
Make sure to visit Ushuaia and make a stop in Tolhuin, Best facturitas in Argentina, and pay a visit to the Falklands via scheduled flight though, very interesting place too, in the Chilean Side don't forget to Overflight Torres del Paine... Amazing one that!...