i shipped an 85 pound suitcase of clothes and misc down here through fed ex and it was more or less a nightmare. it costed something like 700 dollars with Fed ex. then they held it for about 50 pesos a day because i had a "used electric razor" inside. when i went to Ezeiza to deal with it fed ex no longer had my bag but the AR customs did and i had to scramble for 2 1/2 hours between 3 offices before they closed for the day getting seemingly worthless but necessary signatures and stamps on my paperwork until i told to pay my fine. then i had to go to 3 or 4 more people to actually retrieve the bag. when i actually got the bag and they opened it in front of me they didnt know what they were looking for or why they were really holding the bag, i could see it in the guy's face, and when i told him it was just my luggage he just let me go with it never mentioning a razor. so i believe the whole reason it was in customs was because it was a heavy bag and they didnt want to deliver it or really deal with it at all so they make me come down and get it and charge me until i do.
seriously try and have a friend bring stuff down here but if not ship as little as you can. and dont ship oversized things like i did, keep it below 50 lbs maybe around 30-40 at most. not sure the cost on it.
hope this helps!