search both EZE and AEP airports. Heck, even look into flying out of Montevideo, it can randomly be cheaper sometimes. Also search for a bunch of airports in Spain if you're willing to land anywhere in Spain. You can do all of this by using google flights which lets you use multiple airports for both departure and arrival airports. This will maximize the possible itineraries, thus increasing your chances of spotting a deal. Check out the calendar that shows when the prices are lowest if you are flexible on the exact date.