Sound advice. You can add Andes Lineas Aereas to those 2. I just entered some sample dates between BA and Salta and the locals would pay 1349 pesos while foreigners would pay a whopping 4350. I flew with them back in March and the price differential wasn't that much but they do ask you whether you are a non resident on their website.
May I suggest visitors look into using their Lanpass or American miles for domestic flights within Argentina. The cost is normally 20k at Lan and 12k at American and there is normally a fair amount of availability and the ability to change the date at no cost. Great value in my opinion.