I spoke to an argentinian accountant few months ago, he told me that when you inscribe a property for more than U$S 100000 during the process of buying/selling, you have to pay taxes on it, I dont remember the percentage. The notary has the obligation to keep that amount of money to pay the taxes.
I heard from many sources that the process of selling a property is different for an argentinian citizen than how it is for a foreigner, because of the "impuesto a las ganancias" the argentinian pays.
I also suggest you to speak with a lawyer and an accountant before buying the house.