First of all, I never change money back in GBP (my home currency) and as a result I keep "bin ends" of all the foreign currencies I've acquired to use as a starter next time I'm stepping off a plane at that destination. I realise that the ARS you might take home probably won't be worth as much next time you return but to me it's not worth taking the exchange rate hit when selling back currency if I know I'm going to visit again before long. If you are sure you won't be back again for a long time (or ever) try and change only as much into ARS as you intend to spend or spend your leftovers before you go. Check the Banco Piano website and newspapers like Clarin and La Nacion for the latest exchange rates here. USD is the preferred currency to exchange here so decide for yourself whether you might be better off buying USD in France with your Euros and changing them here for ARS. For a couple of years or so I was significantly better off by changing GBP into USD in the UK and then changing USD to ARS here.
