I have been told by a notary that I basically have to "convince" them. The same notary asked be for a letter from a lawyer or accountant legalized by apostille and translated and legalized here too. But I too have read that a bank letter is enough ... so I'm now shopping around for another notary to see what they say.
The bank today told me I had to speak to Depto Comercio Exterior 0810 999 9090 for any transferral of funds INTO argentina and that they would indicate which forms to fill out and would probably ask for a bank statement. But, I think I'm going to wait until I find an escribano with some experience in these matters,
Please post your experience here as I am interested too...