Hi Irene, flying to Calafate and Salta is the best way but if you don't mind travelling for 16h in a cama (bed) bus to Iguazu I'd recommend it as the route is quite nice (buses include meals and drinks)... Flights in Argentina are expensive for foreign travellers as Aerolineas Argentinas is practically the only airline in the country (Lan Argentina is starting with some routes and less schedules but prices are about the same). In the past it was a good deal to buy tickets once in the country or to a local travel agency instead of any pass, but now you will have to compare. Try to contact Aerolineas Argentinas UK and see if they can offer you a good deal purchasing International flights with them as well. If not, send a request to
www.peruforless.com for a quote, the company can offer you land services for good prices as well. I'm from Argentina and work at PFL, so any kind of info you may need, just let me know.