To the O.P
The price of property in Argentina is in USD. this means you pay the exact price as agreed up with seller in USD - CASH or USD - transfer in USD to his USD account abroad or in in USD denominated account in Argentina.
However, the catch is that the price in the sale deed is put in pesos as per the offcial exchange rate prevalent by the central bank. For example, Lets say you buy a house today priced at 100,000 usd by the seller. you will carry 100,000 usd in CASH to the office of the Notary magistrate or where ever you have decided to sign the lease. However, the amount put in the sale deed will be 7,500,000 pesos and NOT 1,7000,000 pesos which is the real value. This means, when the times comes to sale, your tax liabilities or Capital gain tax will be based on appreciation from 750,0000 pesos to the value in official pesos value on day of the sale. Your property taxy ( bien personales) will be based on 7,500,0000 pesos value and not on 1,7000,000 pesos value.
The amount of commission to real estate agent and to the Notary magistrate will be in USD based on real USD value and as defined by percentage agreement with them. None will accept offcial pesos value for their commission.
It means - all persons involved in the deal will only accept USD cash. And all documentation/taxes/excesses basis Government rules will be done basis official pesos rate.
Hope all clear. Feel free to ask me any more questions.