When I first came to Argentina way back in 05 my mum would send me stuff through the post 3 or 4 times a year. Apart from the fact that I always had to collect it from Retiro, I never had any issues and rejoiced in receiving tea bags, hp, marmite and the like. Always came through undamaged so it can be done, but man I just don't trust the system any more. Good luck if you do try! Hopefully if it goes well you will be inspired to open up a Brit food shop in Bs As. That said I talked to the lady in Santiago Chile who runs the British food shop over there and she said that even in Chile it was a massive pain in the arse getting stuff through the Chilean customs. So I can only imagine what it would be like here.